SAN FRANCISCO (CBS SF) — San Francisco’s mayor and health director urged residents Tuesday to do whatever is necessary to avoid another post-holiday surge in COVID cases that would be “catastrophic.”

Mayor London Breed and Health Director Dr. Grant Colfax noted during their weekly news conference Tuesday that the recent stay-at-home orders are having an effect in blunting the rate of increase in cases.

“While our cases are still high, we have some data that shows people in San Francisco have been moving around less over the past two weeks,” said Breed. “That means that people are being mindful and doing their best to comply.”

However, Breed said hospitalizations remain as high as they ever been and the city is “in a very dangerous place” if there is another post-holiday surge as was seen following Thanksgiving.

Currently in San Francisco, Breed said there were 20,976 total cases, with 173 currently hospitalized and 176 total deaths.

Colfax said the collective efforts of citizens to avoid gatherings, wear masks and stay at home except for essential activities has slowed the rate of new cases, but the city is still averaging 275 new cases a day, the highest since the start of the pandemic.

“This has been a long and hard road, and as we continue through this holiday season I know it is likely to get harder for many of us. Unfortunately, the situation remains dire. The virus is running rampant across the state,” said Colfax. “Many behaviors we have gotten away with in the spring or summer are much riskier now. There is so much more virus out there, that the likelihood of coming into contact with someone asymptomatic with the virus but still infectious remains higher.”

With the entire state of California seeing widespread transmission, Colfax warned that letting one’s guard down as many apparently did during the Thanksgiving holiday would result in a surge on top of an existing surge.

“Let’s not have the situation that we had right after Thanksgiving – a massive surge that increased cases by 50%. Given where we are now, we simply can’t afford that, and that would be catastrophic.”

When the limited stay-at-home order was issued two weeks ago, new COVID cases were increasing by 8% a day on average. Now, the city is seeing a 2% percent increase in daily cases. Colfax said the changes in behavior are responsible for the case rate change and the vigilance needs to continue to reverse the trend.

To illustrate the point, Colfax noted the R-effective, or reproductive rate of transmission, was at 1.45 on December 6 and 1.24 on December 20. Anything over 1.00 means the rate of infection is growing; below 1.00 means infections are lessening. While the fractional change appears minimal, Colfax said the result is the projected hospitalizations drop from 1,490 to 590, and the projected deaths drop from 544 to 214.

“In the next two weeks, if we reduce the reproductive rate below one, we would have 74 additional deaths here in San Francisco compared to an estimate of 214. Through our actions, if we can get the reproductive rate below one, we are saving hundreds, hundreds of people from being hospitalized. Pause for a moment, think about those numbers, the lives we could save and the hospitalizations we could prevent if we continue to work together and stay home,” said Colfax.

Both Breed and Colfax struck a hopeful note throughout the news conference and repeatedly appealed to citizens to stay home and not gather with people outside one’s household, wear masks and do what is necessary to reach the day where things can begin to return to normal.

“This isn’t going to last forever,” said Colfax. “The new year brings hope and is filled with possibilities of what we can do. Our destiny for 2021 is in our hands.”