San Francisco and the rest of the Bay Area have bounced back into the CDC's yellow tier indicating "moderate" COVID transmission, down from the orange tier — and following a number of weeks when San Francisco County has bounced between the two.

San Francisco's seven-day rate of new cases per 100,000 residents was 23.82 as of Monday, down considerably from 53.66 on Friday, which had us in the orange tier. And by the city's metrics, SF's seven-day average of daily new cases has been continuing to slide downward in recent days after a short blip last week.

San Francisco's daily new cases since Mar. 2020. Source: SFDPH

San Francisco's public health officer and health officers in seven other counties around the Bay Area have agreed to lift the mask mandate again for restaurants and other businesses once a county reaches an 80% or better vaccination rate for all residents of all ages, and once the county has been in the CDC's yellow tier for three consecutive weeks. Marin County met these criteria two weeks ago, however Marin's case rate has fluctuated slightly in the last week or so.

Governor Gavin Newsom today touted the fact that California's test-positivity rate for COVID had hit 1.9%, which is now the lowest in the nation once again. And according to New York Times data, California is in the bottom fifth of states with the lowest daily case rates along with much of the south — California has a daily new case rate per 100,000 residents of 12, while Texas's rate is 11 and Louisiana and Florida currently have rates of 9 and 7, after particularly brutal summer and early fall months that saw surges in hospitals in both states.

"We're starting to see a decline in hospitalizations and ICUs, and some stabilizing of our case rates," Newsom said while at an event in SF's Mission District to encourage more vaccine uptake in Latinx communities.

Newsom also boasted that "4.96 million Californians have received a booster shot" to date, reflecting 20% of the state's adult population — most of whom were vaccinated more than six months ago, between January and May. Studies out of Israel have shown that the effectiveness of both the Pfizer and Moderna mRNA vaccines begins to wane after five or six months — and everyone who got the Johnson & Johnson vaccine initially is being told by public health officials to get a Pfizer or Moderna booster. Mixing and matching with boosters — particularly if you got Pfizer shots initially and now can get Moderna — has also been shown to significantly boost immunity against the virus.

As SFist reported last week, thanks to high vaccination rates, hospitalizations of severe COVID cases have come down significantly in the Bay Area, reaching lows not seen since early July. Hospitalizations in the last two days have ticked slightly upward, but remain at four-month lows.

Related: Bay Area COVID Hospitalizations Hit Lowest Count Since Early July