Under recently released federal guidelines, a COVID-19 vaccine can be authorized for use if it is safe and proves effective in as few as 50% of those who receive it. And “effective” doesn’t necessarily mean stopping people from getting sick from COVID-19. It means minimizing its most serious symptoms, experts say.

“We should anticipate the SARS-CoV-2 vaccine to be similar to the influenza vaccine,” said Dr. Kathleen Neuzil, director of the Center for Vaccine Development at the University of Maryland. “That vaccine may or may not keep people from being infected with the virus, but it does keep people out of the hospital and the ICU.”…

Developing a vaccine capable of inducing “sterilizing immunity” — that is, the ability to prevent the virus from causing an infection — takes time and research, which might not be possible as death tolls continue to rise and the recession grows deeper. Yet with so many companies on the hunt for that vaccine, there is hope one of them might actually achieve it.