There's a chance the vaccine could offer some protection against COVID-19 itself, says virologist Robert Gallo, who directs the Institute of Human Virology at the University of Maryland School of Medicine and is chairman of the Global Virus Network.

The key is getting the right flu vaccine, says Gallo, who was one of the main scientists credited with discovering HIV. "The vaccine has to have a live virus in it. The virus is attenuated so it doesn't cause disease, but otherwise the virus is alive."