I THINK IT’S SAFE TO SAY THAT THE VACCINES HAVE BEEN OVERSOLD: Studies show COVID-19 immunity from Pfizer vaccine wanes after 2 months. That said, I question whether antibody levels are a good metric for immunity, since we know that T- and B-cell mediated immunity seems to be the key to Covid resistance.

Related: “The natural immune protection that develops after a SARS-CoV-2 infection offers considerably more of a shield against the Delta variant of the pandemic coronavirus than two doses of the Pfizer-BioNTech vaccine.”

Plus: Vaccinating people who have had covid-19: why doesn’t natural immunity count in the US?

“Starting from back in November, we’ve had a lot of really important studies that showed us that memory B cells and memory T cells were forming in response to natural infection,” says Gandhi. Studies are also showing, she says, that these memory cells will respond by producing antibodies to the variants at hand.

Gandhi included a list of some 20 references on natural immunity to covid in a long Twitter thread supporting the durability of both vaccine and infection induced immunity.12 “I stopped adding papers to it in December because it was getting so long,” she tells The BMJ.

But the studies kept coming. A National Institutes of Health (NIH) funded study from La Jolla Institute for Immunology found “durable immune responses” in 95% of the 200 participants up to eight months after infection.13 One of the largest studies to date, published in Science in February 2021, found that although antibodies declined over 8 months, memory B cells increased over time, and the half life of memory CD8+ and CD4+ T cells suggests a steady presence. . . .

Real world data have also been supportive. Several studies (in Qatar,15 England, Israel, and the US) have found infection rates at equally low levels among people who are fully vaccinated and those who have previously had covid-19. Cleveland Clinic surveyed its more than 50 000 employees to compare four groups based on history of SARS-CoV-2 infection and vaccination status.18 Not one of over 1300 unvaccinated employees who had been previously infected tested positive during the five months of the study. Researchers concluded that that cohort “are unlikely to benefit from covid-19 vaccination.” In Israel, researchers accessed a database of the entire population to compare the efficacy of vaccination with previous infection and found nearly identical numbers. “Our results question the need to vaccinate previously infected individuals,” they concluded.

And yet.