The World Health Organization's chief scientist says Americans may not start getting back to a "Pre-COVID" lifestyle until 2022.

Experts say having an approved vaccine could help that become a reality, but when will you be able to get one?

Dr. Robert Redfield says face masks are the most powerful tool the U.S. currently has against COVID-19.

"If we did it for six, eight, 10, 12 weeks, we'd bring this pandemic under control," says Dr. Redfield, of the CDC.

Dr. Redfield says a limited vaccine supply may be accessible later this year. However, for the general public, probably not until the late second or third quarter of 2021.

President Donald Trump disagrees with that timetable.

"We are ready to go immediately as the vaccine is announced. It could be announced in October, it could be announced a little after that," says President Trump.

Vice President Mike Pence says a viable vaccine is progressing quickly.

"As soon as the FDA says it's safe and effective we will have tens of millions of doses available for the American people," says Pence.

The push for a vaccine comes as the U.S. heads into the flu season.

"I'm very concerned that the next few months may be amongst the worst months that we have experienced," says Dr. Larry Brilliant, an epidemiologist.

Dr. Anthony Fauci, a member of the White House's Coronavirus task force, tells the Wall Street Journal the U.S. is unlikely to have a vaccine by October, but says November or December is more realistic. But he added that if too few Americans get the shot, it won't prevent the virus from spreading.

The updated guidance will allow eligible visitation in approximately 500 of the state's 613 nursing homes.