Name: Why another COVID surge could hit the Bay Area in the months ahead
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Why another COVID surge could hit the Bay Area in the months ahead

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In so many respects, it’s looking like the worst of the pandemic may be over for the Bay Area.Hospitalizations from COVID-19 and positive test rates have dropped significantly, too. Many counties reporting plummeting case counts are rapidly reopening. San Francisco may , the second-least-restrictive, in just two weeks.At the same time, Bay Area counties are getting deliveries of the Johnson &amp; Johnson vaccine, and the vaccination rollout at large continues to improve.But even amid good news, experts still warn: Another surge may still be on the horizon.Dr. John Swartzberg, a UC Berkeley infectious disease expert, gives the likelihood of another surge a 45% chance. If it occurs, it will hit at the end of March and into April, he says.“The type of surge that I think we’ll see will be nothing like we saw in the terrible, dark days of late November and January,” Swartzberg said. “But it will be another surge.”Dr. Peter Chin-Hong, a UCSF infectious disease expert, has a bleaker prediction: The likelihood is 100%, he said.“The question is not whether or not we’ll get a surge, but by how much,” Chin-Hong said. The Bay Area is in the middle of the “honeymoon period” it’s experienced before — a tranquil period of five to eight weeks in between surges. That can breed complacency.UCSF biostatistician Travis Porco has been running simulations to figure out if and when another surge is coming. He looks at rising vaccination rates, plus variables such as increased viral transmission, which can accompany reopening and relaxed adherence to health guidelines. His math shows a possible fourth surge within 30 to 40 days.“On the whole, things are so much better,” Porco said. “But it’s not done. We don’t want to turn our back on the monster. It’s got a few more tricks up its sleeve.”One more variable to consider is variants. The more the virus is able to spread, the more it can collect mutations that could make it less vulnerable to vaccines or more infectious. A more infectious variant first found in the United Kingdom already is spreading in parts of California, and a homegrown variant that may also spread faster than the original virus has exploded across the state.“Every time it’s a roll of the dice that it could get worse,” Porco said.Back in September, virus numbers dropped throughout the Bay Area after a summer surge, and counties slowly began reopening with a familiar glimmer of hope. The week of Sept. 13, eight of nine Bay Area counties dropped from purple to the red or orange tier. In San Francisco, indoor dining returned Sept. 30, right before the county reached orange status.That euphoric week, the rate of daily new cases was about 6 per 100,000 residents in San Francisco. It’s currently about 4.5 cases per 100,000. The seven-day case average in California at the time of the fall reopening was 3,231, lower than today’s rate.But the fall optimism, and the associated reopening, were short-lived.A month later, those case numbers started increasing in all counties. In San Francisco, by early November, about a month after indoor dining and other restrictions were eased, the case rate was back up to 9 per 100,000. By Oct. 23, the statewide seven-day average topped 4,000 and continued to soar.The timing couldn’t have been worse as the surge coincided with gatherings around Thanksgiving and Christmas. The state hit its worst seven-day average of 45,214 cases three days before Christmas.The fourth surge is likely to come, experts say, in part because B.1.1.7 — the so-called U.K. variant — will be the dominant coronavirus strain by the end of March. It’s 50% more transmissible.Another reason is the psychology of where people are right now in the pandemic: so close to what feels like the end, even if it actually isn’t.“We’ve been so beaten up in those dark days, and we’ve been so elated with the dramatic drop in the number of cases, that people are now being less careful about the three pillars of masking, social distancing and not getting together in crowds,” said Swartzberg.Coronavirus PandemicThe third reason has to do with movement at large — with more states opening up too quickly, what happens in Texas doesn’t stay in Texas, experts say. Or, in Las Vegas, for that matter, one of the top three destinations where Californians are zeroing in on summer travel, according to data and Google trends.And the combination of travel and holidays can lead to movement of variants, said Shannon Bennett, chief of science at the California Academy of Sciences.“Traveling and holidays also imply gathering, maybe in a closer manner than normal,” she said, “so that could provide additional opportunities for transmission.”COVID ResourcesTracking COVID-19 cases across the Bay Area and California.Experts say the surge is likely to look very different from the summer and winter surges, because of several variables: vaccinations, variants, immunity from natural infection, and reopening.Vaccinations are likely to keep hospitalizations and deaths down, meaning another surge would likely put less strain on hospitals, and in particular intensive care units. And it will likely result in far fewer deaths.Depending on the county, roughly 10% of people in the Bay Area have received two doses of vaccine and are fully vaccinated, but thousands of young people will not be eligible for at least two months.With spring break on the horizon, and the weather getting warmer, the main drivers of the spread will likely come from unvaccinated young people, particularly on college campuses or people looking to travel for the break, experts say. UC Davis is offering for students to avoid nonessential travel during the upcoming vacation.Data shows younger people are often asymptomatic carriers, and the Bay Area is seeing an overall decline in testing behaviors. Those factors mean the surge this time might be more prolonged, though less visible, experts say.“It’ll be more like a hill, with a long rise, as opposed to a peak,” said Swartzberg.Coronavirus ResourcesAlso, more than a year into the pandemic, natural immunity for many who were infected with the coronavirus may soon be waning, which could lead to thousands of reinfections in the next few months, some infectious disease experts say.Seven of the Bay Area’s nine counties are now in the red tier — meaning that most residents can now dine, see a movie, work out and visit museums indoors. On Wednesday, Gov. Gavin Newsom said the state is working on adding a green tier to the reopening system.But with more movement comes more spread.“A lot of people focus on the individual risk prevention strategies, but I think what drives numbers going up as a nation, including regionally in California, is movement,” said Chin-Hong.Annie Vainshtein and Matthias Gafni are San Francisco Chronicle staff writers. Email: ,COVID ResourcesTracking COVID-19 cases across the Bay Area and California.

In so many respects, it’s looking like the worst of the pandemic may be over for the Bay Area.Hospitalizations from COVID-19 and positive test rates have dropped significantly, too. Many counties reporting plummeting case counts are rapidly reopening. San Francisco may , the second-least-restrictive, in just two weeks.At the same time, Bay Area counties are getting deliveries of the Johnson &amp; Johnson vaccine, and the vaccination rollout at large continues to improve.But even amid good news, experts still warn: Another surge may still be on the horizon.Dr. John Swartzberg, a UC Berkeley...

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Annie Vainshtein

Matthias Gafni

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Why another COVID surge could hit the Bay Area in the months ahead

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