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.
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