(11.11.2020)

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.