Is the city headed for a fourth wave? Three doctors and a data scientist weigh in.

In wake of loosening restrictions in San Francisco — and the end of the pandemic presumably in sight — experts are split on whether the city is headed toward a fourth surge in cases.

Some of the disagreement stems from the number of unknowns and the impact of each, including vaccination rates, the potency of variants, pandemic fatigue and the behavior of other states. The city’s move to the red tier last week, followed by Gov. Gavin Newsom’s announcement that the reopening tier system would change to include a vaccine metric, further impact predictions.

Even if the city is on track for a fourth wave, experts emphasized that such an outcome is not inevitable, and if the right precautions are taken — masks and distancing — any surge could be avoided.

“The first thing to do is acknowledge that this is a distinct possibility,” said Dr. John Swartzberg, a UC Berkeley professor emeritus of infectious disease and vaccinology. “The second is to do something about it.”

And if there is a fourth surge, vaccines will likely render it less deadly as the winter surge. However, Dr. Peter Chin-Hong, an infectious disease expert at UCSF, warned that the long-term effects of Covid can still be devastating to some who are infected but don’t end up in the hospital.

“It’s much better to not get Covid — this seems like a no-brainer, but it can’t be overemphasized,” he said.

Chin-Hong commended what he sees as a measured reopening by San Francisco. But he said “the writing is on the wall” for a fourth wave, pointing toward states such as Texas and Mississipi that last week lifted all coronavirus restrictions. He’s worried cases from these states could spill over into California, especially with the upcoming spring break for college students.

“The virus doesn’t know any borders,” he said.

Swartzberg disagreed that the city’s reopening pace was sound. The decision to reopen indoor dining, museums and other non-essential businesses with limited capacity was premature, he said. Similar reopenings, he pointed out, preceded the first, second and third surges.

“To quote Einstein, ‘The definition of insanity is to keep doing the same thing over and over, expecting different results,’” he said. “I think our approach is insane. I feel strongly about this, but I hope I’m wrong.”

Not all experts see a fourth wave in the future. Dr. Monica Gandhi, an infectious disease specialist at UCSF, said that easing restrictions — at least in the way California is doing — is the right thing to do.

“If you look across the entire country at the rate at which cases and hospitalizations are going down, it’s not a gentle curve, it’s coming down quite fast, especially the hospitalizations,” she said. Nationwide, cases have dropped by 12 percent and hospitalizations by 28 percent over the past two weeks. In San Francisco, cases are down by 43 percent over the same period of time. 

Much of the disagreement around re-opening seems to be around the issue of variants – how quickly a new variant can spread and the effectiveness of the vaccines against the variants. On the latter, new science comes out every week and much of it is comforting on the efficacy of the vaccines against new variants.

Swartzberg said there’s “no question” the more-transmissible UK variant will become the dominant strain in California, he said. 

Gandhi’s unconcerned about the variants: “If they were that much more transmissible, we wouldn’t see the steady decline in cases in California,” she said. “Those are hard numbers belying any concern that the variants will hurt our progress.”

She also cited a recent paper from the University of California, San Diego that finds that current vaccinations protect against infection from variants by generating strong T-cell immunity in addition to antibodies. 

Peter Khoury, a data scientist with a P.h.D. from UC Berkeley, shared similar concerns as Swartzberg with regard to the city’s reopening. He said all three past surges followed lifted restrictions on dining, which serve as a proxy toward the population’s attitude toward reopening. He especially sees similarities in the shape of the second and third wave’s curves, which both followed the reopening of indoor dining.

“The more you reopen, people have a tendency to become complacent and do more socialization, and the more socialization, the more upward pressure there is on the curve,” he said.

He expects new case counts to flatten by mid-March and that cases will start to rise in April.  Because of reporting delays, the city will know whether cases flatten by the end of March and if cases start to rise by mid-April. If average daily new case counts fall below 30 and stay there for more than four weeks — the city’s current seven-day average is 52 — Khoury says it could indicate that the pandemic is coming to an end.

Khoury acknowledged that vaccines could put downward pressure on such a surge, but even if the city doubled the rate at which it administers vaccines, the city wouldn’t reach herd immunity until well into the fourth surge. 

Part of the variation in opinions on a fourth wave, Gandhi said, is based on what scientists are choosing to measure as a problem. Her focus is on severe disease that requires hospitalizations, whereas others are more concerned about case counts. But thanks to vaccinations, she anticipates rates of severe disease will continue to fall.

All who were concerned about a fourth wave said it could be avoided, and routine precautions could still save lives. 

Swartzberg added, “We don’t have a lot of control over the variants, but we do have control over whether we wear masks, whether we social distance or get together in congregate settings.”

“If we do all those things, there’s a good chance we could avoid a fourth wave,” he said.