Getting vaccinated for COVID-19 won't provide immunity from the public health directives to wear a cloth face mask in public.

"We are going to be in this mask phase well into 2021," predicted Dr. Anthony Harris, associate medical director at occupational health firm WorkCare. "It won't be until fall of next year that you'll begin to see masks not being a part of our normal day-to-day, at the earliest."

The U.S. Food and Drug Administration has authorized two COVID-19 vaccines so far, including Moderna's vaccine, which got a green light Friday. Randomized clinical trials involving more than 70,000 people documented 94 to 95% fewer cases of COVID in adults who got vaccinated vs. those who received a placebo.

Yet at least 11 people who got the Moderna vaccine and eight who got a vaccine made by Pfizer later ended up with COVID, study data show. No other vaccine is expected to be submitted to the FDA before the last part of January.

Experts say masks will be needed well into the future, despite vaccination, because no one yet knows whether vaccinated people can have asymptomatic cases and spread the virus.

Also, scientists don't yet know how fast immunity might fade or whether booster shots will be needed after the initial two-injection course.

"The unknown in all of this is, what is the duration of that protection?" said Dr. Mark Sannes, an infectious disease specialist with HealthPartners. "It would be great news if a booster wasn't needed ... but I think we should assume that will not be the case and prepare accordingly."

The high number of deaths from COVID-19 in Minnesota continued to moderate on Sunday, with 70 added to the tally. The state has seen 4,850 fatalities from the viral respiratory illness since March.

The deaths added Sunday include 45 residents of long-term care or assisted living facilities. All of the deceased were at least 55 years old.

Mid-December has proved to be the deadliest period of the pandemic so far. Minnesota's average number of fatalities per day surpassed 60 for the first time on Dec. 11 and remained above that level until Sunday, when the seven-day average dropped back to 58.

Yet the average number of new cases of COVID-19 has been dropping. The seven-day average new-case count peaked just above 7,000 on Nov. 20 and stood at about 2,600 on Sunday.

The proportion of COVID tests coming back positive is also dropping, which public health officials consider a good sign. Sunday's seven-day average test-positivity rate fell below 7%, less than half the November peak of 15%.

Although a Dec. 16 executive order from Gov. Tim Walz extended the ban on all indoor bar and restaurant service through Jan. 10, state officials let fitness clubs and outdoor dining and drinking establishments reopen Saturday at lower capacity.

Amateur sports may resume practices (but not games) on Jan. 4 under the order, and elementary schools statewide can restart in-person education on Jan. 18 if they meet conditions such as requiring staff to wear face shields and masks.

State officials don't recommend gathering on Christmas or New Year's Eve. But the modified guidelines do allow indoor groups of up to 10 people from two households, or outdoor gatherings of up to 15 people from three households.

Masking and social distancing are encouraged at any gathering, even if some attendees are taking part in a vaccine clinical trial or are health care workers who have received their first vaccine shot.

"Right now, [to] everybody who has been vaccinated, I would still say to wear a mask," said William Hanage, an associate professor at Harvard's Center for Communicable Disease Dynamics.

Hanage estimated that 50 to 60% of Americans will need to be fully immune to COVID to reach the point where the virus cannot invade the population — the "critical vaccination threshold."

It's still not clear when kids and teens will be able to start contributing to herd immunity by getting a vaccine.

Neither of the authorized vaccines has definitive data on safety and effectiveness in people under 16, and there's no existing timeline for when the ongoing studies will conclude.

Will kids be able to get the vaccine at all next year?

"I'm optimistic," said Dr. Tim Schacker, vice dean for research at the University of Minnesota Medical School. "I mean, look at what we did in 2020. We went from not having any idea of what was going on to [now having] two vaccines."

Joe Carlson • 612-673-4779