Featured Post

Is the new professionalism and ACP's new ethics really just about following guidelines?

The Charter ( Medical Professionalism in the New Millennium.A Physician's Charter) did not deal with just the important relationship of ...

Sunday, July 11, 2021

Masks and social distancing in the vaccinated elderly

 The CDC, when it lifted its mask recommendation, stated that- in general- people who have been fully vaccinated do not  need to wear masks except in certain situations such as planes,trains and hospitals and contact with the elderly and immunocompromised  They further said that one " should consider" wearing a mask if you have a condition that weakens your immune system" or if you lived in an area of the country where the infection rate was high.(High was not defined by the CDC).The "not wearing masks" was heard and little else was remembered and the take home message was the long awaited "take off your masks".

Remembering back to the early days of the pandemic in 2020 we were told that it was a priority to protect the vulnerable which was taken to mean the immunocompromised and the elderly. 

Were the elderly ignored in the surprise turn around from the CDC's mask guidance? They did not seemed to be specifically mentioned.

In an earlier blog posting I commented about two studies that addressed the immune status of the elderly following Covid vaccination and I wrote the following:

"Muller et al (1) conducted a cohort study on subjects less than 60 years of age and those over the age of 80 who received the Pfizer vaccine. Specific IgG antibody tiers against SARS-COV-2 spike protein were lower in the elderly and the elderly had no detectable neutralizing antibodies. In the younger group 2.2% had no detectable antibodies."

A large Danish Cohort study (2) compared vaccine effectiveness in health care workers and long term care patients. After the second dose the effectiveness in the patients was 64% ( 95% CI  14-84) while in  health care workers the   effectiveness was 95% (95% CI  82 -95. The median age of the 39 040 patients was 84 and there were 488 PCR confirmed cases of SARS-COV 2 cases. If this study can be generalized the widely quoted 90 % plus vaccine efficacy does not apply to the elderly. It should be noted that may well represent the worse case in that the eldely in long term care are a less resilient group that 80 years old independently lived in the community. Note  also sometimes  I am saying effectiveness and sometimes efficacy, they sound alike but in epidemiology they are terms of art and mean different things. More on that below. Also see footnote 1 for explanation of efficacy.

More data on that topic of how well vaccines really work. has  become available.

Jablonska et al (3) published a pre print estimating the " real life " impact of vaccination on covid mortality using data from 31 European countries and Israel from the period from Jan 2020 until April 2021. They found the vaccine effectiveness  in terms of  protection against death was equal to 72%.

Note: The Jablonska article seemed careless  ( it is a preprint after all) in the use of the words "effectiveness" and "efficacy" in that sometimes the authors said effective and sometimes efficacious in reference to their study. In the jargon of epidemiology "effectiveness " refers to real world data , i.e. how a medical intervention in used outside of a randomized clinical trial (RCT)  .The results of a RCT are expressed in terms  of efficacy.   The results of the  RCTs for the Covid vaccines are expressed as efficacy.`

The Danish cohort study and the Jablonska paper were non RCT data and expressed them major metric as effectiveness,


For prevention of severe disease Pfizer,Moderna as well as AstraZeneca and Novavax reported a 100% 
efficacy. 

Why is there such a difference.As the authors suggest age of the populations studied varied.
Only 24.7 % of subjects in the Moderna trial were equal to or older than 65 years of age and 42% of Pfizer trial subjects were over 55 years  of age and only 12.2 % were over  55 in the AstraZeneca trial.


In regards to a medical intervention the disease reducing ability as indicated from the results of a RCT is  always better and correctly expressed as efficacy than that observed when the intervention is utilized outside of the confines  of a RCT and which is correctly expressed as effectiveness. This is very well known .

A number of the public health experts appearing on TV  may have forgotten that when they emphasized  the 100% efficacy against death  that was reported in the randomized trials. It was extrapolation beyond the data to claim or at least hint  that everyone who would be vaccinated would be protected from serious illness  and death. Whether this was intended or not I believe many people were lead to believe when fully vaccinated they were almost guaranteed not to have serious or fatal covid 19 regardless of how old they are on to what degree there may be covid spreading in the community and whether or not that spread may be driven by covid variants such as the Delta variant. 

When I heard repeatedly that the mRNA vaccines were 100% effective against death after the several month duration trials were published I shuddered because I assumed that at least some of those experts knew that the effectiveness of a medical intervention is never at high as the efficacy demonstrated in a clinical trial.  

In early July the Health Ministry of Israel announced that the Pfizer vaccine now seem 65% effective in decreasing symptomatic and asymptomatic disease and 93% effective in preventing hospitalization and death.Several deaths were reported in fully  immunized patients.

From personal experience involving  acquaintances  and family it seems that the  many of the over 75 year old crowd have eagerly accepted the need- no- mask advice since they have been vaccinated and are not known to be immunocompromised and believe that masks and avoiding crowds are no longer necessary.It is not that simple although it was very easy to take away that impression from the CDC announcements.
 
I would have preferred that  the CDC at least  recommend that the immunocompromised consult with their  oncologist or hematologist, a number of which, I believe, are recommending that their patients have their antibody levels checked and in some cases take a third shot. One group in France has taken that approach with their solid organ transplant patients and given third shots which had generally demonstrated a significant increase in antibody levels which were typically low after the standard two doses of the mRNA vaccines.  As for the elderly perhaps they should have been advised to consider the level of vaccination in their community as well as the number of cases of the Delta variant before they go mask free to do things like dining out in inside eateries and attend indoor sporting events.

Of course  the fully vaccinated can gather together for food or singing or whatever and be very unlikely to get sick. This quite different from singing and drinking in bar or a crowded restaurant  in a locality  with 20% vaccination rate and increasing cases of  covid19 from a variant. 

Cases still soar world wide and more have died in 2021 from covid than in all of 2020,India and South America  are hot beds  and cases are increasing in Japan preventing live spectators in the upcoming Olympics  and for lack of vaccine much of Australia is in some form of lockdown.In parts of the world with low or zero vaccination rates variants will develop and air travel links everyone with everyone in the world. The more contagious Delta variant is already over 50% of cases in US and increasing particularly in areas with low vaccination rates.



1)Muller,L et al Age-dependent immune response to Biotech/Pfizer BNT 162b2 COVID-19 vaccination Clin infect Dis 2021 Apr 27

 2)Moustsen-Helms,IR et al Vaccine effectiveness after 1st and 2 nd dose of the BNT162b2 Covid-19 Vaccine in long term care facility residents and healthcare workers A Danish cohort study. Pre Print from Medrxiv 09 March 2021.

3)Jablonske,K et al The real-life impact of vaccination on covid-19 mortality in Europe and Israel. MedRxiv ( this is a pre print and at the time of publication had not been subject to peer review.

 Footnote 1.

Efficacy refers to the proportional reduction in disease attack rate between ARV and ARU, where ARV is the attack rate of the vaccinated group and ARU is the attack rate in the unvaccinated group.

Risk ratio is the ratio of ARV/ARU

Vaccine efficacy is 1-RR expressed as a percentage.

For example if in a given time frame 100 of unvaccinated get the disease and 5 in the vaccinated  group get the disease  we have 1-5/100 = .95 or expressed as a percentage of 95%. 

To put vaccine efficacy in some context we see that in  the 2018-2019 season the flu vaccine has a 29% efficacy .Measles vaccine is about 97% efficacious. 



2 comments:

Nicolas Martin said...

I was going to tweet this to @erictopol, but I find he has blocked me. I’ve no idea why, but he’s apparently easy to offend.

Nicolas Martin said...

I was going to tweet this to @erictopol, but I find he has blocked me. I’ve no idea why, but he’s apparently easy to offend.