How Effective Are Covid-19 Vaccines Really? It’s Complicated

Covid-19 vaccines flirted with perfection at first. Reality is more complicated

STAT NEWS – When Covid-19 vaccines were reported last fall to be roughly 95% effective at preventing symptomatic Covid-19 infections, the world rejoiced — and even veteran scientists were blown away.

Very few vaccines are that protective. Those made to fend off viruses like SARS-CoV-2 — viruses that invade the nose and throat, like flu — typically aren’t at the high end of the efficacy scale.

That was the good news. Now, however, our soaring expectations for Covid-19 vaccines are in the process of sinking back to earth.

With the more transmissible Delta variant of SARS-2 circulating, it is increasingly apparent that, even if mRNA vaccines like Pfizer’s and Moderna’s offer impressive protection against severe Covid infections, they aren’t going to prevent infections in the upper respiratory tract of some proportion of vaccinated people.

“The vaccines are wondrous weapons, but they aren’t impenetrable armor.”

Kathryn Edwards, a vaccine expert at Vanderbilt University, told STAT:

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“We all wish that that this would be gone. That we would get a vaccine and … we would control it. But I think that looking back, probably that wasn’t always realistic.”

There are still open questions about exactly how much less protection mRNA vaccines may be providing.

Evidence of the downward creep of their efficacy is based in part on as-yet-unpublished data from Israel, one of the first countries to vaccinate a high percentage of its elderly.

Ran Balicer, director of Israel’s Clalit Research Institute and one of the scientists involved in this research, said the group has seen a decline in vaccine effectiveness since the Delta variant started to take off in the country.

But figuring out what is behind that — waning immunity? Delta’s increased transmissibility? The advanced age of the Israelis who were first vaccinated? A combination of those factors? — is very challenging, he said … READ MORE. 

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