People’s immunity against seasonal coronaviruses — those that cause the common cold — fades quickly. That’s why you can catch a cold again and again.
But the vaccines developed against the SARS-CoV-2 virus, which causes COVID, appear to be creating high levels of antibodies that protect even as they wane.
In one recent study of 3,900 health care workers tested weekly for COVID, about 5% tested positive between December and April, Poland said. But of 204 who fell ill, only 16 had been fully vaccinated against COVID-19.
“You’re talking about a 0.3% rate” of infection in fully immunized people, Poland said. “And if they were vaccinated, and if they had breakthrough infections, they had viral loads that were 40% to 50% lower and were almost 60% less likely to have any fever. If they were sick enough to be in bed, they spent two fewer days in bed than the unvaccinated.”
And that’s the major factor in deciding whether boosters will ever be needed: Are vaccines succeeding at their most important job?
“The goal of this vaccine is to keep you out of the hospital and out of the ICU and out of the morgue, said Dr. Paul Offit, director of the Vaccine Education Center at the Children’s Hospital of Philadelphia and an advisor to the U.S. Food and Drug Administration.
By that measure, experts like Poland and Offit now think it’s unlikely that boosters will be needed any time soon for most or maybe all those who have been vaccinated.
Even in the face of newer and more infectious variants like the Delta variant that emerged in India, the existing vaccines have been able to prevent severe illness among the fully vaccinated, Poland said.