Tuesday, November 9, 2021

Studies confirm Covid-vaccine protection waning

Study shows dramatic decline in effectiveness of all three COVID-19 vaccines over time | Los Angeles Times - Melissa Healystaff:

November 4, 2021 - "As the Delta variant became the dominant strain of the coronavirus across the United States, all three COVID-19 vaccines available to Americans lost some of their protective power, with vaccine efficacy among a large group of veterans dropping between 35% and 85%, according to a new study. Researchers who scoured the records of nearly 800,000 U.S. veterans found that in early March ... the three vaccines were roughly equal in their ability to prevent infections. But over the next six months, that changed dramatically.

  • By the end of September, Moderna’s two-dose COVID-19 vaccine, measured as 89% effective in March, was only 58% effective.
  • The effectiveness of shots made by Pfizer and BioNTech, which also employed two doses, fell from 87% to 45% in the same period.
  • And most strikingly, the protective power of Johnson & Johnson’s single-dose vaccine plunged from 86% to just 13% over those six months. 

"The findings were published Thursday in the journal Science.

"The three vaccines held up better in their ability to prevent COVID-19 deaths, but by July — as the Delta variant began to drive a three-month surge of infections and deaths — the shots’ effectiveness on that score also revealed wide gaps. 

  • Among veterans 65 and older who were inoculated with the Moderna vaccine, those who developed a so-called breakthrough infection were 76% less likely to die of COVID-19 compared with unvaccinated veterans of the same age. 
  • Older veterans who got the Pfizer-BioNTech vaccine and subsequently experienced a breakthrough infection were 70% less likely to die than were their unvaccinated peers. 
  • And when older vets who got a single jab of the J&J vaccine suffered a breakthrough infection, they were 52% less likely to die than their peers who didn’t get any shots.

"For veterans younger than 65, the Pfizer-BioNTech and Moderna vaccines provided the best protection against a fatal case of COVID-19, at 84% and 82%, respectively. When younger veterans inoculated with the J&J vaccine suffered a breakthrough infection, they were 73% less likely to die of COVID-19 than were their unvaccinated peers."

Read more: https://www.latimes.com/science/story/2021-11-04/study-shows-dramatic-decline-in-effectiveness-of-covid-19-vaccines

Read study: https://www.science.org/doi/10.1126/science.abm0620

Covid: How long does vaccine based immunity last? | Sebastian Rushworth MD

November 5, 2021 - "It’s unfortunate that the drug companies decided to end their trials early, by giving active covid vaccine to the members of the placebo group after just a few months.... This means that we are instead forced to rely entirely on observational data as we try to understand how safe and effective the vaccines are over the longer term. That is why a recent study out of Sweden is so very interesting. It is currently available as a preprint.... The purpose of the study was to determine how effective the vaccines are at protecting against covid over the longer term.... 

"The authors of the study began by identifying all people residing in Sweden who had been fully vaccinated against covid-19 by late May 2021 [who] were then matched individually against people of the same age and gender, and living in the same municipality, who hadn’t been vaccinated. In total, 1,684,958 individuals were included in the study. They were followed until October to see if they developed covid-19....

"[T]he vaccines were very effective at preventing symptomatic covid around two months out from vaccination. This is what the randomized trials showed.... Overall, the reduction in relative risk at 31-60 days out from vaccination was 89%. However, after those first two months, there was a rapid decline in efficacy. At four to six months, the vaccines were only reducing the relative risk of infection by 48%!... One vaccine did still provide a better than 50% relative risk reduction at six months – the Moderna vaccine. At four to six months, the relative risk reduction with the Moderna vaccine was 71%. Pfizer was at the same time point only offering a 47% reduction in risk, and AstraZeneca was at that point not doing anything whatsoever to lower risk....

"By the nine month mark, the Pfizer vaccine is no longer offering any protection whatsoever against symptomatic covid-19. Unfortunately, nine month out data isn’t offered for the Moderna vaccine due to the small number of people for whom that information is currently available, but at six months out, the Moderna vaccine’s ability to prevent symptomatic covid-19 had dropped to only 59%. So there is a continuous decline in effectiveness at each time point measured even for the Moderna vaccine, without any sign of levelling off....

"People over the age of 80 initially show a good response to the vaccine, with a 73% reduction in relative risk of disease at one to two months out from vaccination. However this drops to only 50% at two to four months, and by six months there is no benefit whatsoever. Even for the middle aged (50-64 years) ... the vaccines are completely ineffective at preventing symptomatic disease by the four to six months mark. The only group for whom the vaccines are more than 50% effective by the four month mark is people under the age of 50 (for whom effectiveness at four to six months is 51%)....

"At one to two months out from vaccination, the vaccines provided a 91% reduction in risk of hospitalization or death. By four to six months, that had dropped to 74%. And from six months out, the reduction was down to 42%, although the difference between the vaccinated and unvaccinated group was no longer statistically significant. In other words, at the six month time point it was no longer possible to detect a statistically significant effect of vaccination on risk of hospitalization or death....

"As I see it, there are two possible explanations for the rapidly declining effectiveness of the vaccines. The first is that it’s due to ... the vaccines themselves, and the second is that it’s due to ... the rise of the delta variant. If the second reason is true, then there is no reason whatsoever to give people boosters, because the boosters won’t do anything to improve immunity. If the first reason is true, then there is a case to be made for boosters, although it feels pretty absurd to give everyone a booster every four months to protect against a virus that for most people is little more than a cold.... There is however a pretty good case to be made for regular boosting of the multi-morbid elderly every four months, preferentially with the Moderna vaccine....

"The vaccines are much less effective than was initially believed, and effectiveness declines rapidly. With that being the case, the idea that it’s going to be possible for countries to vaccinate themselves out of the pandemic is clearly nonsense. The only way the pandemic ends is by enough people getting infected and developing natural immunity, which is the same way every prior respiratory virus pandemic has ended."

Read more: https://sebastianrushworth.com/2021/11/05/covid-how-long-does-vaccine-based-immunity-last/

Read study: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3949410

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