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…. 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.
Anna Durbin believes the high bar set by the results of the Phase 3 clinical trials of the Pfizer and Moderna vaccines is now negatively impacting U.S. vaccination policy.
“I think these vaccines are a victim of their own success,” said Durbin, a vaccine researcher in Johns Hopkins Bloomberg School of Public Health. “Now we expect perfection. And if it’s less than perfect, we want a booster.”
