Reports spread across the country can play a cruel irony: someone tests positive for the coronavirus, even though he has already received one or both doses of the Covid-19 vaccine.
Notable examples
It happened to at least three members of Congress recently:
But this has been reported in people in other walks of life as well, including Rick Pitino, a Hall of Fame basketball coach and a nurse in California.
How can this happen?
Experts say that cases like these are not surprising and do not indicate that there was anything wrong with the vaccines or how they were administered. Here’s why.
-
Vaccines do not work instantly. It takes a few weeks for the body to build up immunity after receiving a dose. And the vaccines now in use in the USA, by Pfizer-BioNTech and Moderna, require a second injection a few weeks after the first to achieve full effectiveness.
-
Nor do they work retroactively. You may already be infected and not know when getting the vaccine – even if your test has recently been negative. This infection may continue to develop after you receive the injection, but before your protection is fully established, and then appear in a positive result.
-
Vaccines prevent disease, but perhaps not infections. Covid vaccines are being authorized based on how effectively they keep you from getting sick, needing hospitalization and dying. Scientists still don’t know how effective vaccines are at preventing the coronavirus from infecting you or preventing you from passing it on to others. (This is why vaccinated people should continue to wear masks and maintain social distance.)
-
Even the best vaccines are not perfect. The efficacy rates of the Pfizer-BioNTech and Moderna vaccines are extremely high, but they are not 100 percent. With the virus still spreading out of control in the United States, some of the millions of people recently vaccinated were doomed to become infected anyway.