Israel is the
test group because, as a country, they were fully vaccinated before any other country; starting in Dec 2020 with the older adult population. In August 2021, 8 months later, the Pfizer vaccine has a severely reduced effectiveness. This is the argument for booster shots starting approximately 6 months after second shot:
Now, the effects of waning immunity may be beginning to show in
Israelis vaccinated in early winter; a preprint published last month by physician Tal Patalon and colleagues at KSM, the research arm of MHS,
found that protection from COVID-19 infection during June and July dropped in proportion to the length of time since an individual was vaccinated. People vaccinated in January had a 2.26 times greater risk for a breakthrough infection than those vaccinated in April. (Potential confounders include the fact that the very oldest Israelis, with the weakest immune systems, were vaccinated first.)
"Israel, which has led the world in launching vaccinations and in data gathering, is
confronting a surge of COVID-19 cases that officials expect to push hospitals to the brink. Nearly 60% of gravely ill patients are fully vaccinated.
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At the same time, cases in the country, which were
scarcely registering at the start of summer, have been doubling every week to 10 days since then, with the Delta variant responsible for most of them. They have now soared to their highest level since mid-February, with hospitalizations and intensive care unit admissions beginning to follow. How much of the current surge is due to waning immunity versus the power of the Delta variant to spread like wildfire is uncertain.
What is clear is that
“breakthrough” cases are not the rare events the term implies. As of 15 August, 514 Israelis were hospitalized with severe or critical COVID-19, a 31% increase from just 4 days earlier. Of the 514, 59% were fully vaccinated. Of the vaccinated, 87% were 60 or older. “There are so many
breakthrough infections that they dominate and most of the hospitalized patients are actually vaccinated,” says Uri Shalit, a bioinformatician at the Israel Institute of Technology (Technion) who has consulted on COVID-19 for the government. “One of the big stories from Israel [is]: ‘Vaccines work, but not well enough.’”
A grim warning from Israel: Vaccination blunts, but does not defeat Delta