Masking could also help prevent the spread of the virus to children too young for vaccination and people with weak immune systems.

“Personally, I continue to wear a mask when going into public spaces outside of my household, both for my own protection and for the sake of my community,” said virus researcher Angela Rasmussen of the Vaccine and Infectious Disease Organization at the University of Saskatchewan.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University, said a “belt-and-suspenders” approach also makes sense for people who are older or have health issues and are more vulnerable to getting severely ill if infected.

“I’m pretty healthy, but I do have gray hair. So when I go out to the supermarket, I’m masked,” Schaffner said.