How a Covid-19 Vaccine Could End Up Helping the Virus Spread
It may be possible to infect others even after getting a shot.
A vaccine that protects against symptoms of Covid-19 could contribute to the spread of the disease if—and this is still just an if—the people who get vaccinated remain capable of carrying and transmitting the virus. That’s a risk that’s gotten little attention amid the deserved jubilation over a Nov. 9 report from Pfizer Inc. and BioNTech SE that their vaccine candidate appears to be highly effective.
It’s a matter of timing. If everyone in the world is vaccinated, or has developed antibodies through exposure to the disease, there will be no problem. But in the early going, when only some people are protected, they could unwittingly spread the disease to people who are still vulnerable. The vaccinated people might stop wearing masks and social distancing since they aren’t themselves at risk anymore. They could be carrying the SARS-CoV-2 virus, even if they’re not getting sick from it.