Holiday travel raises COVID reinfection risk. Here's what to know – San Francisco Chronicle

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Holiday travel raises COVID reinfection risk. Here’s what to know. People wind their way in a queue line created by stanchions at a security checkpoint at San Francisco International Airport on Wednesday.
Risk of COVID reinfection rises this winter. Here’s what to know. Sherri Gholami of San Francisco pulls her luggage behind her as she joins the end of long line at a security checkpoint in the International Terminal at San Francisco International Airport on Wednesday, June 15, 2022 in San Francisco, Calif.
People line up for a security check at San Francisco International Airport on June 15, 2022. Winter holiday travel will likely contribute to an expected upsurge in COVID-19 cases into the new year.
It’s the third holiday season since the pandemic began and, as in previous years, millions of Americans are traveling for Thanksgiving, Christmas, Kwanza and other winter festivals.
This time around, the public health guidance is different. Almost three years into the crisis, COVID prevention measures such as mandatory masking and social distancing have largely been lifted. Most Americans have been vaccinated, many have gotten booster shots and at-home test kits are widely available.
Still, experts expect a pickup in COVID cases during the winter as people travel all over the country and gather indoors with friends and family. Along with the coronavirus, hospitals are also dealing with two other infectious diseases this year — respiratory syncytial virus and the flu — that are hitting early and hard, straining hospital capacity.
Given how many Americans have now had COVID one or more times, a critical question on peoples’ minds during the holidays is how much risk they face of getting reinfected. Here’s what experts have to say:
“COVID cases will rise due to holiday travel, that’s a given,” said Dr. Peter Chin-Hong, who specializes in treating infectious diseases at UCSF. “Reinfection depends on a few factors, not only the virus but the variants, when you were last vaccinated, what your risk of severe diseases are, how long since you’ve had COVID,” he said.
Chin-Hong emphasized that risk varies from person to person and that many COVID cases this winter could be reinfections. But the scale of the problem is hard to tell due to the fragmented nature of tracking on the local, state and national levels. COVID infections are already on the rise in California: an average of 5,483 cases per day were reported in the state over the past week, according to the New York Times tracker, up 40% from two weeks earlier. The California Department of Public Health could not provide The Chronicle with current reinfection estimates, but said that during the summer peak driven by earlier omicron strains, around one in seven Californians was reinfected with COVID.
Fully vaccinated people have a lower risk of reinfection. But since 2021, when vaccines first became available, the recommended time frame between the original shots and suggested boosters has shrunk as new virus subvariants emerged. The Centers for Disease Control and Prevention originally recommended getting a booster around six months after being vaccinated. Now, with omicron strains that show greater ability to evade immunity, that window has shrunk. According to Chin-Hong, a reasonable time frame to be considered “safe” since your last vaccination, booster shot or infection is currently about three months.
It depends on behavior, said Chin-Hong. Gatherings should ideally be held in well-ventilated spaces, he said. If traveling, he suggested focusing your efforts on situations where you’re the most vulnerable, including in the cab to the airport, lining up at security, going to the food court, purchasing something that requires touch for payment, using the bathroom, sitting at the gate and boarding. Other people may not be masking even if you are. “If we continue to see poor behavior, we will see more and more cases,” he said.
As of the latest figures, nearly 60% of COVID cases in the U.S. are attributed to BQ subvariants of omicron. Descendants of BA.5, the BQ.1 and BQ.1.1 strains have mutations in their spike proteins that help them evade immunity created by vaccines and prior infections. For the week ending Nov. 26, the CDC estimates that BQ.1 and BQ.1.1 were causing more than 57% of new COVID-19 cases in the US., but it’s unknown how many of these were reinfections. While there’s some evidence that the newer subvariants are more infectious than earlier strains, they don’t appear to be more virulent.
A recent study published in Nature Medicine found that risk of negative outcomes such as hospitalization, organ failure and death from COVID-19 rose with repeat infections compared with patients who were newly infected — regardless of vaccination status. Other research has suggested higher risk of long COVID among people infected multiple times. Chin-Hong, who was not involved in the Nature Medicine report, pointed out that the subjects were all over 60 and had underlying health issues. “This study sounds scary,” he said. But if reinfections do affect some people more voraciously than others, he said, it’s “not the case for most on a larger scale.” Still, he advised prudence. “Be vigilant; COVID is still around,” he said.
Local health officials, including Dr. Jeffrey Smith, county executive officer in Santa Clara County, are urging people to use the original precautions against infection — washing hands, getting vaccinated and boosted, masking, social distancing and staying home if you’re unwell or testing positive — to prevent reinfection. “We really have a major problem with having COVID and the flu and RSV hitting us all at the same time. COVID is not gone,” he said in a statement. “We’re seeing decreasing availability in ICUs across the county. Get your vaccine in as quickly as you can, wash hands, mask, and continue to socially distance,” he said.
Shwanika Narayan is a staff writer at the San Francisco Chronicle. Email: Twitter @shwanika
Shwanika Narayan covers Bay Area economic trends, culture and communities at The San Francisco Chronicle. She previously covered retail, small business, e-commerce and trade on the business desk. Before joining the paper in 2019, she worked at The Los Angeles Business Journal and freelanced for AJ+, NBC News, Quartz and Hyphen magazine, covering business news, and general national and global news. Shwanika has a master’s degree in journalism from Columbia University and a bachelor’s degree in political science from UCLA.