Although the ideal Covid-19 vaccine would completely prevent infection, a shot that reduces severe illness and mortality is still a success, Naor Bar-Zeev, deputy director of the International Vaccine Access Center at Johns Hopkins University, said Wednesday.
“The best ideal candidate would be reducing infection and transmission in the community, and that would eventually result in herd protection,” he said, speaking at a Johns Hopkins briefing. “If we have a vaccine that reduces mortality and makes this whole pandemic a milder one, that’s also a success."
Herd immunity, which is when enough of a population is immune to an infectious disease that the spread from person to person is unlikely, is not on the cards for the next few years, Bar-Zeev said, as the number of doses available of vaccine will be insufficient to produce it.
“What we want to do is reduce severe disease among the people at highest risk,” he said. “So a vaccine that does that but allows infection to carry on, you know causing a mild cold, fantastic, bring it on, that’s wonderful.”
He also pointed out that herd immunity would require more than just an effective vaccine. It also requires community participation and coverage.
“If 50% of Americans don’t want to be vaccinated, for example, because of hesitancy or safety concerns, then even a 100% effective vaccine won’t achieve herd immunity,” he said.