Pacemakers generate electricity and tons of data , who monitors the data

 Recently I had my pacemaker replaced.This process is often erroneously refered to as  getting a new battery when in fact it is replacement of the IPG (implantable pulse generator). The IPG consists of the battery,the software  and connectors to the leads. The process takes about 1 to 2 hours and generally the recovery process is quicker than the implantation itself of the pacemaker as arm movement does not have to be as restricted.

Typically, every three months a "remote interrogation" is done. Data is downloaded from the pacemaker and then transmitted to in my case to the Medtronic computer  system and from there to either my physicians office or again in my case to  a third party organization who  then sends an interpretation of the data to my doctor's office.It appears that both the third party company and my EP doc's office can earn a fee approved by Medicare for the report review.

The third party interrogation monitoring company typically sends me a copy by secure Google email of the interrogation. For several reasons which I have written about before I find it important to actually  see my report as opposed to receive a message that " every thing is OK" Or " if you don't here from us everything is OK". The Cures Act now mandates that physicians and hospitals must give the patients copies of lab work and even clinical notes in  a "timely" manner or face hefty fines. Patients no longer have to accept the " we will call if something is not OK" from their doctor. 

The reports themselves are not that difficult to understand as least in regard to a pacemaker versus a ICD (defibrillator). some of the important values to review are: capture voltage,lead impedence ( resistance,)arrhythmias and battery life estimation. The pertinent data can be reviewed quickly .

While the basic data seem to be  well monitored I am less sanguine about the regular occurrence of a review of the  optimal settings for such things as pulse amplitude and pulse duration  and review of arrhythmias flagged by the unit's algorithms. In my case my interrogation report indicated several episodes of AF (atrial fibrillation). This finding lead to a fair amount of concern about having runs of AF but I learned later that the  unit's algorithm misidentified  "far field sensing" as AF. Far field sensing refers to the atrial lead sensing activity from the ventricular lead and double counting of atrial signals. 

Phantom physical exam reports continue to proliferate in the strange world of the electronic health record

 Recently,I learned that nurse practitioners as well as physicians are authorized to post  the results of physical exams that were not done in the medical record (EHR) 

The narrative of the encounter  I had with NP was accurate and fairly detailed and I actually learned a lot about how the thousands of remote device interrogation are reviewed in their department.

 Although one of the reasons for the visit was to check the surgical wound (I had a pacemaker replacement one week before) there was no mention of that in the EHR report of the encounter although the NP did glance at the surgical site.  I was described as having no edema and having normal pulses but those findings were fictional. A similar fictional physical exam was detailed in the pre op visit one week earlier with the EP cardiologist. (Actually I do have a trace of ankle edema at the end of the day and my posterior tibial artery is very hard to palpate.)

When I attended medical school in an earlier century my teachers emphasized the importance of transcribing a physical exam and other clinical findings as accurately as possible and that the medical record was a legal record and could be subpoenaed. The medical record is the basic legal document in medical malpractice litigation. 

Why would a bogus physical exam description be routinely inserted into the EHR as that occurrence appears to be the case. If it is done to be able to "upcode" the record why would the practice not be fraud?

Other than an intent to defraud, what else could explain the profusion of bogus system reviews and physical exams. Simply put it may be a unintended consequence of the EHR and the quality movement, Standard boiler plate material is generated by the EHR to fill the need to comply with the increased demand for documentation of "quality "clinical work. The alleged intent was to have clinicians edit out activities not performed.However,that has not been the outcome as through inattention or in some cases perhaps intent the fictitious exams remain displayed in medical records awaiting a plaintiff lawyer to ask Dr. Did you perform a physical exam on a certain date?

addendum: 3-15-2022 I learned from someone knowable in current Medicare charges and EHR vagaries that Medicare no longer pays more if a physical exam is performed and charges are earned based on time spent and case complexity. So there would be no monetary advantage to charting a physical exam or system review but the phantom exams seem to still be appearing in EHRs.

Status report Covid 19 in Texas at end of 2021

 From my vantage point in Houston everything I see here validates my decision to urge a relative not to travel here  from Paris for Christmas. 

Cases soar and  emergency rooms are packed,Drug stores have sold out of the home antigen tests and the state is out of (or almost out of ) the only antibody treatment that is effective for Omicron (sotrovimab). Houston's county health agency urges people to not go to the ERs to get a covid tests and to use masks in congregate settings.

The Texas Medical Center reported for the week of December 20th a positivity rate of 15.4 % versus  6.2% for the previous week and  201 Covid admission versus 101 the previous week. 

The two prescription medications approved by the FDA for out patient treatment of Covid 19 are yet to arrive in the state . A number of eateries have closed due to the lack of staff and New Year's Eve is approaching and from what I see mask wearing is not prevalent, The Christmas church services  whose live streams I sampled did not seem to require masking in spite of the recommendation of the CDC and county health authorities. By contrast the Pope's Christmas mass had everyone wearing a mask. 

On a positive note, a number of centers have been designated to administer Evusheld, This is an antibody cocktail to be given IM every six months to prevent infection in immunocompromised patients which received an EUA in early December.

President Biden has just said there is not a "federal solution" to the developing crisis and defers to the state Governors. Residents of Texas may find little comfort in that as Govenor Abbott has by executive action and legislation taken steps to minimize masks use by schools and vaccine mandates by state schools and by businesses. I hope  I am wrong but Texans are not likely to see Covid mitigation actions coming from Austin. By contrast the govenor of Connecticut  has ordered the national guard to  distribute N 95 masks and antigen test kits.

Apparently both the Delta strain and the Omicron variant are circulating, one being much more contagious and the other more virulent  and physicians have no quick way of distinguishing between the two. 

All we can do is pull up the draw bridge and hope to not have a medical emergency and not deplete too much psychic energy lamenting and asking the question how  could the richest country in the world end up where we are now. 

Addendum 12/31/21.As of 12/31/21 Walmart and Sam's Club Pharmacies in Texas have both Paxlovid and Molnupiravir available with prescription from physician. 

Without durable individual immunity you cannot even talk about herd immunity

 In the early days of the covid 19 pandemic there was much speculation about what percent of the population would have to be vaccinated in order to achieve herd immunity )(HI). It seemed to be a matter of not if but when HI would be accomplished.

Writers made analogies to  measles and smallpox for which vaccination programs achieved herd immunity and in the case of smallpox, eradication. If HI could be achieved  for a  very infectious disease such as measles spread by aerosols, why not covid 19?

Theoretical considerations regarding HI center on the basic reproduction number (R naught or Ro which is the average number of people that one infected person will infect.  The number of people needed to be immunized in order to reach HI is 1-1/Ro.For example-if the Ro is 2 then 50% would have to become immune (either through vaccination or infection) for a Ro 0f 3 we see 1-1/3 equals 2 thirds or 67% 

Several simplifying assumptions underlie the formula for HI including that all individuals have an equal opportunity to become infected. Epidemiologists disagree as to what exactly HI is and as to what the necessary assumptions are in estimating a HI vaccination level.

However the key-typically implicit- assumption is that being vaccinated ( or recovering from an infection) results in long lasting immunity.(1)

We now know that this major assumption does  not conform with reality. We now know that fully immunized individuals can become infected and can transmit the disease and also  that recovery from covid 19 infection does not preclude becoming infected again. 

The idea underlying HI is that as individuals become vaccinated ( or recover from infection) they are removed from the susceptible pool. With covid vaccination or infection  both groups seem to be removed from that pool only for a time , perhaps as short a time as 6-8 months. While infection blocking immunity (nasal mucosal immunity) wanes quickly the disease reducing immunity seems to be more durable.

When cases of abreakthrough infection became recognized as a real thing,some in the public health sector  said  " well, the vaccine was only intended to prevent serious disease and death".But if that were the case why was there so much  talk about achieving herd immunity a concept that IMO only makes sense if the vaccine prevents spread.

Dr Jennie S Levine has been quoted that she and her colleagues talk about transient herd immunity.

My thought on that is perhaps we are seeing a transient HI for example now In Louisiana and Texas .Both states had a major Delta surge with a surge of cases and hospitalization and death and now the surge seems to have abated.Possibly as more and more people were vaccinated and more infection plus mandatory NPIs (in Louisiana ) the number of susceptible individual decreases to reach some level of transient herd immunity like condition. However, as immunity wanes again in states with a large number of unvaccinated individuals serving as a covid reservoir some level of spread could occur again  for another round of surges . Are we likely to continue to see regional whack a mole events .

A much more optimistic scenario is that the booster shots will bring about a sufficiently long period of immunity so that more than a transient herd immunity could be achieved. In other words- the covid 19 mRNA vaccine should have been a three shot vaccination  program all along.  

1)Core Concept: Herd immunity is an important—and often misunderstood—public health phenomenon | PNAS

How big will the US covid winter surge be?

The epidemiology  predictors at IMHE made their prediction for the 2021 winter on a tweet published November 5.

Based on three factors they predicted there will be a winter surge but, of course its magnitude is unknown.

The factors are : 1) seasonality 2) waning vaccination immunity 3)less caution by the public,We think we know the direction of these vectors but what about their magnitudes?

As time goes on not only vaccine immunity will fade but so will the immunity of previous covid 19 infection  both of which seem to fade in about six months.   Countering that direction is the number of people receiving the booster shots.Countering that is the relentless barage from right wing media claiming that the vaccines are either dangerous or worthless.

Meanwhile in France and Germany a new surge seems underway and travel restrictions to to the US have been lifted. What could possibly go wrong?

Dr. Michael Osterholm is quoted: "Any effort to predict future course beyond 30 days relies on pixie dust for its basis" and we all remember what Yogi said about predictions particularly for the future.

Cardiac fibrosis in endurance athletes

 There have been a number of reports of cardiac fibrosis in endurance athletes. It turns out that these reports pertain to areas of late gadolinium enhancement in right ventricular insertion points.Some explanation is required . To begin with-all forms of fibrosis are not the same.

Gadolinium is the contrast agent  used in MRIs.It accumulates in the extracellular space and lights up on a cardiac MR and is called Late Gadolinium Enhancement (LGE)

LGE is seen in myocardial infarctions in necrotic areas with scars consisting of replacement fibrosis.LGE has also been reported in hypertrophic cardiomyopathy (HCM) ,pulmonary hypertension and more recently in a number of long time highly trained endurance athletes.In these three conditions the underlying pathology is not replacement fibrosis  (as is seen in a myocardial infarction scar) but rather plexiform fibrosis and myocardial fiber disarray and is typically seen at the insertion points or hinge points where the right ventricular wall inserts on the interventricular septum. 

Sato et al (1) proposed  that paradoxical motion of the interventricular septum is a primary mechanism for late gadolinium enhancement (LGE) at the ventricular insertion or hinge points.

LGE at ventricular insertion points has been described in pulmonary hypertension and in a number of highly trained endurance athletes .It is unlikely that paradoxical septal movement explains the LGE at hinge points in these athletes although it may be  true in the cases described by Sato.

DeBosscher et al (2) found LGE at the hinge points in young and older highly trained endurance athletes but found no evidence that LGE was associated with any structural,functional or electrical problem with LGE at the insertion points which they found  28% of the 233 athletes studied.

LGE was first described in  older endurance athletes   but now this data demonstrates that younger runners may also have that finding and that it is not a uncommon findings in highly trained runners and its long term significance remains to be determined. I suppose the fact that the LGE does not represent replacement fibrosis  with its associated risk of reentrant ventricular tachycardia  is good news.However,data is lacking as to the long term consequences (if ANY) of LGE at the RV insertion points in long time endurance athletes regarding reentrant rhythms or other clinical problems. 

1) Sato,t et al Paradoxical motion of the interventricuar septum as a primary mechanism of ate gadolinium enhancement at ventricular insertion points. Int J Cariol 2012;158 (1) 156-7 

2)De Bosscher, R et al Hinge point fibrosis in athletes is not associated with structural, functional or electrical consequences;a comparison between young and middle aged elite endurance athletes. Euro Heart Journal, 41,supp 2, Nov 2020 

What is the threshold for exercise induced cardiac remodeling (EICR)

 It has been known for over 100 years that physical exercise  may cause heart enlargement.A study of Harvard rowing team members described cardiac enlargement in an 1899 issue of the Boston Medical Surgical Journal.  

There have been numerous cross sectional and longitudinal studies documenting the structural changes in the heart associated with high levels of aerobic exercise.These  are enlargement of all four chambers and mild to moderate increase in the left ventricular wall thickness and an increase in left ventricular mass index- a condition referred to as eccentric hypertrophy to be distinguished from the concentric hypertrophy characteristic of strength building exercise. 

How much exercise is required to bring about that remodeling? Is  eccentric remodeling observed in runners whose activity  level is far less that that required  to be competitive in a full triathlon ?

Dawes and associates  (1) have provided some answers.They performed cardiac mri s on 1096 volunteers and linked  the mr results with their self reported exercise habits over the previous 12 months. They divided the exercise histories into four categories with category 1 being essentially no regular aerobic exercise and category 11 defined as less than or equal to 3 hours per week. They found that there was no statistical difference between category I and category 11 in regard to cardiac MR findings/

So one 'take- home" from their study might be  that exercise less than 3 hours per week is not likely to be associated with any exercise related structural cardiac changes. 

Moreover they found that increasing activity levels were significantly associated with increased ventricular end-diastolic volumes and left ventricular mass index

However, minutes exercised is not the only variable related to EICR which is likely related to some summation or interaction between intensity, frequency and duration. One could speculate that someone doing 3 hours of high intensity interval training per week  might well induce a bit of EICR and that someone doing 8 hours of slow walking in the park per week may probably would not

1) Dawes TJW Moderate physical activity in healthy adults is associated with cardiac remodeling.Circ Cardiovascular imaging 2016  se004712  

Has the conservative- libertarian "fusion" been severed by Trumpian authoritarianism ?

 Aaron Ross Powell from Cato Institute writes about the  always fragile "fusion" of conservatives and libertarians becoming increasingly severed. He refers  back to Robert Nozik's observation that  " Liberty disrupts patterns" as at least a partial explanation. 

Conservative- preferred social patterns are disrupted by liberty  So to maintain those patterns conservatives turn to authoritarian means , if not they loose their conservative values. 

What are these conservative values? They generally include family values which mean a man-woman stable relationship,opposition to gay unions,opposition to abortion and a tending to endorse traditional female roles in society, allegedly based in and supported by biblical principles. Additionally conservatives  endorsed  a society that is  largely managed and controlled by white anglo saxon men with opposition to encroachment by black and brown immigrants, preferring things as they once were or  were thought to be at some vaguely defined prior time.

Progressive big government with its ever growing body of liberty limiting regulations is a common foe for conservative and libertarians with conservatives bristling  at bureaucratic rules antithetical  to conservative's preferred social norms and libertarian obviously promoting liberty.

Decisions once made by families and local governments have been shifted to state and then federal government as the locus of decision making, a development well described and critiqued by Thomas Sowell in his book "Knowledge and Decisions ". This central decision making  shift is another common foe for conservatives and libertarians.

Arnold Kling offered a framework for considering the differences between the languages used by progressives,conservatives and libertarians Progressives tend to frame things as there being a battle between the oppressed and the oppressors, while conservatives see things as between civilization and barbarism while libertarians view matters as between liberty and coercion.

In answer to the title question-No Trumpian authoritarianism   did not break the conservative-libertarian fusion as it was a fragile union to begin though arguably useful regarding  certain issues   but his rhetoric may have provided a effective rallying cry (MAGA) and gave the nativists' core of conservatism a person around whom  to rally.

I believe the key insight in Powell essay is that liberty disrupts patterns and conservatives hold certain societal patterns to be important which are put at risk by liberty so conservatives have to jettison liberty to protect their values. In the terminology of Kling the issue  framed for conservatives is barbarism versus civilization and sometimes liberty must be sacrificed to fight off barbarism.Quoting Powell " conservatives have to restrict liberty to retain their social and economic patterns.".

Korean study shows a positive and graded association between physical activity and coronary artery calcification

 A large prospective study (1) from Korea demonstrated a positive relationship between self-reported physical activity and coronary artery calcification (CAC) scores.

There is overwhelming epidemiological evidence that regular exercise is associated with decreased risk of cardiovascular and all-cause mortality.Data indidcate that small amount of exercise is beneficial in that regard and that more seems  better.A panel in 2018 recommended as a minimum 500 met hours per week which is equivalent to 2.5 hours of moderate exercise or 1.25 hrs of vigorous ( greater than 7 Mets) exercise.

Eijesvogel in his comprehensive analysis of the " extreme exercise hypothesis" noted  that the maximum reduction in CV morality was noted at 41 Met hrs per week which is five times the minimum recommended level.  So there is a well defined linear relationship between exercise volume and CV mortality and so far data have not indicated a J shaped curve in that regard.

Defina et al (2) demonstrated that high levels of physical activity ( 3,000Met min per week which is five times the minimum 2018 recommended level) was associated with  prevalent CAC but was not associated with increase in CV disease mortality..Other publicaions have  also demonstrated an increase in coronary calcification in long time endurance athletes .

Sung's article now provides a "positive , graded association between physical activity and progression of coronary calcification, regardless of CAC scores". 

Quoting Sung ;"The standard Agatson CAC scores are calculated as a combination of calcium density and the volume of plaque burden. Higher calcium density,which suggests a more stable calcified plaque, produces a higher CAC score, however it is associated with lower CAD risk."

Both long time endurance exercise and long term use of statins are associated with increased coronary artery calcification  but  lower CV morality.

1)Sung,K et al Physical activity and the progression of coronary artery calcification. Heart 2021;0:1-7,

2) Defina,LF at al Association of all-cause and cardiovascular mortality with high levels of physical activity  and concurrent coronary artery calcifications,JAMA Cardiology, 2019 42 (2) p 174 

Anti Hubris thoughts for medical students-- "our ignorance is boundless"

Sixteen years ago I posted an entry on this blog in which I suggested an anti-hubris courses ( or at least a few lectures) for medical students.

I did not have all the content of this course prepared  (and still have not) but I do have the sense of it and some great quotes which I will sprinkle below.

 The following is a lightly re-edited version of that entry.
 

Most of the  sense of it is from the writings of Norton Hadler and much of it can be found in his article on various European backache compensation systems (JOM,vol 31, pg 823, 1989). In it he speaks of clinical truth which he distinguishes from scientific truth-although scientific truth must be utilized in obtaining clinical truth-and from legal "truth"-which is incidental to settling the dispute at hand. Clinical truth is or is derived from a contract between a physician and a patient and is based on trust.He said it better than I can and his article would be required reading in this "anti-hubris" course.

Our approaches are provisional and based on fragmentary information and when I think about the algorithms and paradigms that are in our tool boxes, Boris Pasternak's quote appears as an emphatic "yes..but", "What is laid down, ordered, factual, is never enough to embrace the whole truth:Life always spills over the rim of every cup". Karl Popper said " we know a great deal but our ignorance is sobering and boundless...all things are insecure and in a state of flux".


All of this does not mean that we can't pull out the latest guidelines from whomever on our smart phone and see if that does or does not apply to the case at hand.But the operative words there are "see if it applies to the case at hand." The experienced physician has one- at least one-advantage over the younger one, he has seen the 180 degree changes in a given algorithm or clinical guideline. Plaintiff attorneys are fond of saying to the expert witnesses ,"Doctor,were you wrong then or are you wrong now" in the situation where there is an apparent contradiction.

Medical students need to know-in regard to the "factual knowledge" imparted to them- that while that material may be the very best that the very best of minds can determine at this time that they need to stay tuned because all of that may change at any time and the physician will have to decide what to do for the patient even before the next authoritative pronouncement is prepared.In that decision she will have to call upon her knowledge,expertise and judgement and the patient's values and views and do her job the way physicians have for many years before guidelines were part of medical language and work with the patient for their particular clinical truth.

"Life is short,the art long and judgement fallacious." is a hard quote to beat.
 .

Still another variation of conduction system pacing -left posterior fascicular pacing

 The right ventricular apex was the preferred site for ventricular activation for pacemakers for several decades.After the realization that apical pacing was associated with an increased risk of heart failure and atrial fibrillation his bundle pacing was rediscovered.Although two cases series of his bundle paced patients were published  in the 1970 s it was not until over forty years later that his bundle  pacing finally began to become established and it was claimed by some electrophysiologists that the era of physiological pacing had  arrived. 

Although his bundle  pacing was considered to be physiologic,it was more technically daunting and typically required a higher ventricular capture voltage.There was also  some frequency of delayed lead displacement  and a shortened battery life paralleled the higher capture voltages.

In 2017 Huang et al described the next development in conduction system pacing-left bundle branch area pacing.  In this technique the sheath is advanced about 1.5 centimeter from the site of His signal recording towards the apex and deeply inserted into the ventricular septum.It is less technically demanding than is His bundle pacing  and requires a lower capture voltage and in some EP centers it has replaced His pacing as the go to conduction system pacing of choice.

 In 2020 Ponnusamy et al (1)described a case in which they were unable to obtain a satisfactory left bundle branch area lead placement and  then maneuvered the lead  2 cm lower and positioned the lead in the area of the left posterior fascicle. A similar case had been described by LJ Zen et al in 2019(2)

The 12 lead EKG with Left posterior fascicular pacing demonstrates a pattern of left anterior hemiblock. 

1) Ponnusany, SS et al. Left posterior fascicular pacing. J Innov Cardiac Rhythm Manage 2021 12 (5) 4493

2)Zeng, l, et al Permanent left posterior fascicular area pacing through the interventricular septum in a patient with infra-Hisian block, Heart rhythm Reports, 2019, Aug 5 (8) 411-413

Long time endurance athletes long time outlook looks good less so for "power" sport advocates

 Dr Runacres (I am not making that up) et al published a meta-analysis of 165000 long time athletes and found , as have other studies, that endurance athletes have lower  cardiovascular mortality and all cause mortality but that does not hold true for long devotees  of power sports. See here 

September 2021- US in another surge in spite of excess vaccine and plenty of masks

 Here we are in another covid surge in the US even though there are no shortages of masks or vaccines.Neither is there a shortage of people who oppose the use of vaccines and masks nor is there a shortage of people seemingly ignorant of the seriousness of the Delta variant driven surge and stress placed on the health care system. 

Neither is there the  previous  official ignorance about the basic transmission mechanisms of Sars Cov2 spread. 

It was not until April/May 2021  that the CDC and WH0 finally abandoned  the primacy of the 100  year old dogmas put forth by Charles Chaplin which said that the basic mechanisms of respiratory disease spread were by droplets and fomites. 

By September  2021 it is well established that Sars Cov 2 can spread in pre symptomatic and asymptomatic people by the aerosol route and that measures directed at droplets and fomites will not suffice. Well fitted high grade masks ( eg.N95s) are needed as well  as mitigation efforts directed along the lines of ventilation, and air flow,  air filtration and air exchange  in indoor settings to complement a vaccination and testing program.

So we know more and should be better  prepared and yet in some parts of the country we are seeing high deaths and hospitalizations. We see parts of the country in which mask wearing is much less than it was in the 2020 surges.Parts of the country that had mask mandates in 2020 now have "anti mask mandates" that prohibit local authorities from imposing mask mandates. Anti mask and anti covid  19 vaccine advocacy flourish on social media and right leaning radio and tv. We know what to do to mitigate the spread of covid 19 but many are defying those measures and apparently many others seem indifferent.

Watching the Astros on TV play at home on in Dallas the optics are the same, virtually no one in the stands wear a mask. even though Covid is surging in Texas.

Whatever effect anti mitigation efforts may or may not be having on the magnitude of the spread  of the Delta variant, its  increased infectiousness has to be considered a primary cause of the latest surge.Delta is clearly more infectious and there is growing evidentiary support for the claim that it is more capable of causing serious disease than were earlier variations. At a time when a more contagious variant is surging we are also seeing surges in ignorance, indifference and political ambition all of which make the  magnitude and speed of spread  even worse. 

Why the US Covid Delta surge may not burn out as quickly as it did in England.

 The rapid uptick and downtick of Delta observed in England has been thought by some to predict  a similar course for the US but the opening of schools may b ae wild card and the Delta surge may not end as quickly as it did in England.

Both Dr. Michael Osterholm and  Dr.Larry Brillant offer a more pessimistic prediction because of their concern that the opening of schools across the country will provide fertile ground for spread and also  offers a platform for virus mutation.

In numerous areas of the country students will not be masked and only a small percentage of high school and primary school kids will be vaccinated. In several states there  has been a concerted effort by the governors and sometimes that state legislatures to issue executive orders and pass legislation  the effect of which is to limit the use of masks and certain other virus mitigation measures in schools and to restrict the right of a private company to  use  " vaccine passports".  

Osterholm in, a recent interview said that a multi layered approach is necessary ..Ventilation is important ( i.e 5-6 air exchanges per hour),as are HEPA air filters and use of proper masks ( e,g, N95 or KN95). Testing students,staff and teachers  several  times a week and removal of positive cases. The importance of airborne transmission makes the popular plexiglass barrier not very effective and may be more for show than efficacy.

The CDC and the American Academy of Pediatricians recommended  masks for school kids.Governor Abbott and Governor Desantis have issued executive orders forbidding local school boards to issue mask mandates.

Another reason that the US might not echo the path taken in England may relate to the different sequencing of vaccination doses.England had a longer period between shot one and shot 2 which has been offered as an explanation for the greater time related decreased in vaccine efficacy in the US versus England and Canada who also opted for the longer time between the 2 doses of the mRNA vaccine.

CDC realizes the vaccinated can spread covid 19 delta variant-now what

 CDC has now seemingly realized that fully vaccinated people can harbor large amounts of the delta variant in their noses and are able to transmit the disease to others. This is a conclusion that could have been reached upon analysis of the Houston Wedding event in which 6 fully vaccinated attendees develop covid  although admittedly there are alternative  less likely explanations for the Houston wedding cases.

In May 2021  when CDC seemed to set people free from mask use the data it had indicated that the likelihood of spread  from the fully vaccinated was low enough to recommend that masks were no longer necessary for vaccinated people under many circumstances.

But by July 29 with access to new data CDC concluded  that fully vaccinated people could  actually spread the disease and that the data they relied on for that conclusion would soon be released. That data is now available Further the greater infectivity of the Delta virus prompted CDC to express a much greater concern.

It now seems that the following should be considered the  operational reality on the ground.

1. Fully Vaccinated people can develop and spread covid 19 delta variant.In the vast majority of cases the disease is either mild or asymptomatic.

2.Some very small  percentage of fully vaccinated people can develop serious and fatal covid 19

3.Delta variant infection results in significantly higher viral loads and infectivity and possibly 

more serious disease. (data from Canada ,Singapore and Scotland  show Odds Ratio for ICU admission range from 3.87 to 4.9 ) 

4.Large areas of the US have relatively low levels of full vaccination 

So practically what does all of this mean.

If you are vaccinated you still  may need to wear a mask.

Why?

Since fully vaccinated people can spread covid wearing a mask protects others. There are two sets of others, the vaccinated and the unvaccinated.  A vaccinated person can contract covid and bring it home to infect children and the elderly. 

If you are not vaccinated you need to wear a mask.Masks should be N95s and ideally covered by a blue procedure or surgical mask.After exposure the mask could  be stored in a container so that they can be used after a several days period of "decontamination "  Adding a face shield to the mask may add another layer of protection although strong supporting data to that point seems not to exist The double mask has not been recommended this time by the CDC but that was recommended for a surge from a Covid version that was less contagious and perhaps less lethal than the delta strain.. Now the CDC advises that the vaccinated should wear masks if they live in a area with a high test positivity rate and a low rate of vaccination.

5.At least some of the geographic  areas cited in item 4 have governors and/or legislators who resist or oppose the standard public health measures used to control epidemics of contagious respiratory disease specifically mask and vaccine mandates. Quantification of the harm that is causing awaits the scrutiny of epidemiologists.

Breakthrough Covid cases-how many vaccinated ? Unvaccinated ?

 In the pre Delta variant era the vaccines were thought to be the answer. The expectation and hope were that a vaccine could provide immunity, stop spread and push us all to the elusive herd immunity and life would return to the pre Pandemic norm.

And for while it  appeared that was the case.As cases numbers dipped lower and lower by the spring 2021 it appears that the worse was over at least in the US and by May  2021 the CDC believed it was time for the fully vaccinated to no longer wear masks with a few exceptions noted ( eg the immunocompromised, in health care setting etc)

But then the Delta variant spread rapidly mainly in the southern states whose vaccination numbers lagged behind. Data from Israel and the US now seemed to indicate that fully vaccinated (FV) people could not only contract Delta but they could spread it.A wedding outbreak in Houston seemed to indicate that fully vaccinated people could spread it to each other. We were learning that Delta was definitely more contagious and data from Canada and Scotland suggested it was also more virulent. 

So while the vaccine promises were not met in some regards it was believed and regularly quoted by the public health and vaccine experts that the vaccine really worked well in that serious disease -the type requiring ICU care,was quite rare. 

Even with or  perhaps because of the unpresented avalanche of covid data published it has been difficult to determine how common are breakthrough cases, how frequent are the serious cases and who does it mainly attack ( is it only a disease of the unvaccinated?) ?  

Data from Israel is instructive. Israel is like an experimental lab for the world.Israel has 78% of its citizens who are over age 12 years fully vaccinated. Most if not all of the citizens are members of one of the HMOs which collect individualized  data which seems to be quickly available for analysis.

Israel is in a Delta surge . A 78% vaccination level is not high enough to prevent Delta surges. 

As of data from August 15 2021 there are 514 patients in hospital. Of those 59% are fully vaccinated  and 87% are over age 60 years. See foot note 1

In Israel serious breakthrough Covid 19 due to delta variation is not rare.

Is serious breakthrough really rare in the US or do we just have not the data to know what is going on with Delta?  Eric Topol and Dr L Wen have been critical of CDC for our flying blind predicament.

Antibody levels have been shown to be decreased at 6 months for both Moderna and Pfizer. Antibody responses in the elderly have been shown to be lower  Does that explain the preponderance of older patients in the Israel ICUs. Increased infectiousness of Delta and decreased antibody levels in patients immunized 6 month or more ago are suspects in regard to delta breakthroughs.intensified by less public attention to masking and distancing.

The case is strong for older folks both vaccinated and unvaccinated to wear masks in congregate settings and the CDC has recommended that as they walked back their May proclamation of no masks for most of the vaccinated.It seeems as if the public heard and remembered the CDC May advice but not their retraction or so it seems based on my personal observation of how few people in Harris County Texas are wearing masks. 

Will the booster fix the covid surge? Well, already Israel has reported 37  breakthroughs  after the booster shot but also have reported strong neutralizing antibody response to a booster mRNA jab. 

 foot note1)

Jeffery Morris (1) offers a illuminating discussion of the Israeli data in which  he demonstrates that when  the overall aggregate data are used the vaccine efficacy is calculated to be lower than it is in either group when the population is stratified  into two groups by age which we are told is an example of Simpson's paradox. His argument is that the "real" VE for serious disease is not as suggested by computing a VE based on the aggregate  data. My take is that  yes  the loss of efficacy for severe disease is not as great as a simple data display would suggest but my main point ,ie the breakthrough cases are not rare, seems solid .

1)Morris,J.  Israeli Data- how can efficacy versus severe disease be strong ... www.covid.data science

Will the current non-plan of "Maybe delta will have a rapid downturn " really work?

 As the delta wave continues to surge steeply upward some optimistic public experts project that US will see the rapid downturn in attack rate noted in England It is nice to think so but...

The US differs from England in at least the following ways:

1.England gave their second dose later than in the US perhaps giving the vaccinated a higher antibody level when Delta landed onshore  

2.  Some or many Brits continued to wear masks even after the controls were lifted.Arguably to a higher degree than in US.

3) England did not have powerful  elected regional leaders actively opposing mask wearing as governors of several  states in the US are now doing.

Dr Eric Topol is critical of the CDC current performance. First CDC was premature in their announcement in May that masks were no longer necesary for the fully vaccinated. The next mistake, in his view and in that of Dr. Leana Wen was to discontinued surveillance of breakthrough cases that were not serious enough to require hospitalization. Further according to Topol they should be doing genomic analysis on breakthrough cases and studying their antibody levels and noting  when and what kind of vaccine they received.  Basically Topol is saying we are flying blind  regarding the delta surge.Additionally CDC is admixing breakthrough case numbers from the pre delta times frame with those of the post delta period giving a falsely optimistic estimate of the fatality rate which in turn tends to negate the impact of their "wear mask again" advice.

From my admittedly limited personal experience in Texas  people just do not seem to be taking the surge seriously. This should not be surprising   One elderly  family friend eats out serval times a week and is now to attend a mini high school reunion Another elderly couple is planning a family union. A large local church is still living by the May CDC recommendations ignoring the most recent CDC advice as well as a recommendations by the county commissioner.Looking over the crowds at the  Astros game, only a few masks are seen. Local  authorities  have been forbidden by executive order to issue mask mandates even though delta is clearly more contagious and arguably more virulent  than the version of covid dominant in earlier surges.

Why does the Pfizer vaccine seem to work significantly less well In Israel

 Data (1) are available regarding effectiveness of   the Pfizer 2 dose mRNA vaccine in Israel,Canada and England/Scotland.

As regards the vaccine effectiveness  (VE) against the Delta variant  there is a wide difference  in the  values for VE for symptomatic disease .For Canada and England/Scotland there are  values of 87 % and 89% versus 64% for Israel.

Both Canada and England/Scotland administered the vaccine not according to the time frame used in the clinical trails for  Pfizer. Due as in part to a  shortage of vaccine in Canada a decision was made to give the second short 4 months after the first .

 In England/Scotland  a similar decision was made to postpone the second shot to maximize the number of  people who received the first shot as the alpha variant was surging at that time.This was done with the realization that they using a dosing schedule different from that used in the clinical trials which is inconsistent with standard method of applying clinical trial results to clinical practice. The British decision was controversial. Some suggested that a partially immune population ( i.e many folks with only a single jab) along with a surge in cases was a set up for a  perfect storm of super surging.

  In Israel, which was not facing a vaccine shortage,the decision was made to give the vaccine according to the time schedule that was carried out in the clinical trials.Also in the US The mRNA vaccines were given according to the time schedule used in the trials.So, will the data for the US show a pattern more like Israel or\more like Canada?

One explanation for the international disparity in vaccine effectiveness  is that the longer delay between doses of the mRNA vaccine results in a more robust  protective response. Could this be another example of "sometimes it is better to be lucky than good"? Perhaps confounding the comparison is the fact that the degree to which Delta was prevalent in the populations varied, i.e.  possibly more Delta at the time of the Israel data compilation. 

1) I based this blog  in part on a slide presented by CDC on or about July 30, 2021 which I believe in turn was derived from several sources including Sheikh,  a. SARs-COV 2-Delta in Scotland.Lancet vol 397 p 2461,June 26 2021 

and an article by B Lopez et al Effectiveness of Covid 19 vaccines against the B.1.617.2 (Delta) variant NEJM July 21, 2021 

Is the US into the 4th ( or 5th) surge of Covid

 Is the US already into the 4th surge of covid pandemic?

Cases and hospitalizations and ICU admission are definitely trending upwards.

Physicians in Alabama,Mississpii,Arkansas and Louisiana are pleading with the public to get vaccinated as they see cases in their hospitals surge and young people are being intubated.

In California, mask mandates are back while in other states governors deny the need and at least one governor (Colorado) said no restriction or mask mandates are necessary until  it is clear that hospitals are being over whelmed. 

It is time already for masks to come back .The CDC mask lifting in May was premature and widely misunderstood and IMO has been  in part, perhaps in large part,responsible for the rise in cases caused by the Delta variant.

The public experts interviewed on TV appropriately emphasize the importance of the unvaccinated getting the jab but if miraculously everyone rushing to the largely empty vaccination sites today it would be over a month before immunity would be obtained. Meanwhile the vaccinated as well as the unvaccinated need to wear mask indoors and in congregate settings. 

The Israeli data and British data differ significantly regarding the effectiveness of the Pfizer vaccine as regards preventing infection (33 %- 88 %) but agree as to a 90 Plus %value for prevention of death or serious illness. But in the worse case scenario many vaccinated persons can contract disease and likely spread the disease making in the short and intermediate term masks and social distancing a high priority. Fully vaccinated parents can contract the disease and spread it to their under 12 year old children who are currently not eligible for vaccination.

Unfortunately until the CDC makes important revisions in its mask recommendations businesses are not as likely to reinstitute mask mandates and masking is essential  until a sea change occurs in the large segment of the population who continues to be vaccine "hesitant". 

Dr. Scott Gottlieb tweeted "CDC has consistently been through,meticulous and late" and that they are not suited to provided quick solutions to emergent problems. He also said CDC's decision to tell the vaccinated that they could unmask was based in part on the demonstrated low risk of a fully vaccinated person to  contract or spread  the earlier variants of covid. That advice clearly does not apply to the Delta variant. 

 

Heavy viral loads with Delta results in greater infectivity setting up 4th US surge

 The 4th covid  wave is already in the US. It is  fueled by the much greater infectivity (1) of the Delta variant  arriving at a time of nationwide reduction in masking and social distancing in part driven by what a increasing number of public  health officials  believe to be a premature and widely misunderstood lifting of the mask mandate\by the CDC.

Some virologists are estimating the R naught of Delta variant to be as high as five. Anecdotal report from Australia indicates that viral transmission occurred with simply passing an infected person in a mall.That seemed to me unlikely until I read of the Chinese study demonstrating a viral load in Delta infected persons greater  than one thousand times that of the original Wuhan strain. Their report found that high viral loads persisted up to 4 days in asymptomatic patients. Asymptomatic spread from  persons with high viral load is pretty  good if not perfect storm for spread in a population who just recently were officially relieved of need to mask or distance.

The report of  transmission of the Delta variant among fully vaccinated people at an outdoor wedding event  in Houston seems to strongly indicate that transmission can happen in fully vaccinated people which should mean that not just the unvaccinated should wear masks in public but so should the vaccinated.

The vaccinated should wear masks in public for two reasons; 1) they can spread the disease to the unvaccinated which includes children who are too young to be currently eligible for vaccine  and of course the elderly and immunocompromised 2)there are "break through" cases  i.e cases in the vaccinated These are usually described as "mild" but some are not and there have been deaths largely in the elderly. 

Israel quickly reacted to increased Delta cases by reinstituting  a mask mandate  as did Los Angles County in California. The medium term answer is more vaccination but the short term answer is masking and social distancing .Already governors in Colorado,Florida  and Texas have said they will not mandate masking for the public and will not "allow"  mask mandates for kids returning to school although that is the recommendation of the American Academy of Pediatrics.

 

With this wave it looks like there will be fewer deaths in the elderly ( mainly because of the higher vaccination rate in the old folks) but reports from Alabama, Arkansas and Louisiana hospitals indicate that ICU admissions and some  deaths are occurring in the younger group. Whether  that indicates a greater lethality  from Delta is not determined at this time.

 

 

1)Viral infection and transmission in a large well-traced outbreak caused by the Delta SARS-CoV-2 variant - SARS-CoV-2 coronavirus / nCoV-2019 Genomic Epidemiology - Virological