Flu season has arrived with a vengeance in the Bay Area, with multiple signs pointing to a potential surge in infections.
This week the San Francisco Health Department reported the season’s first flu-related fatality, as flu-related hospitalizations rose dramatically to 2.39 per 100,000 residents as of Saturday from a rate of 0.12 per 100,000 in the middle of September.
“This sad news reminds us that respiratory viruses such as flu and COVID should be taken very seriously, especially for people who are at higher risk of getting sick,” San Francisco Health Officer Dr. Susan Philip said in an emailed statement Thursday.
Dr. Monica Gandhi, an infectious disease expert at UC San Francisco, told SFGATE by phone Friday that flu activity normally ramps up closer to the winter holiday season, in November or December.
“I’m very surprised by this flu death because that’s very early,” she told SFGATE. “People are just getting their vaccines right now.”
Influenza levels started to rise in the local wastewater last month and currently San Francisco, Palo Alto, Redwood City and San Jose are showing high levels of the virus, according to WastewaterSCAN.
Data released Friday by the California Department of Public Health shows flu tests in the Bay Area are also coming back positive at the highest rates for the state, with near-10% positivity.
In 2024 and 2025, it took until December for the flu hospitalization rate in San Francisco to reach the same high reported this week.
Gandhi noted that in recent years the Bay Area has seen high numbers of hospitalizations related to the flu, especially among very young children who are at higher risk.
“This kind of tragedy should be a prompt to get the flu vaccine,” she said of the fatality. Flu “is still very serious for high-risk groups.”
Dr. Matt Willis, an infectious disease expert and former public health officer for the Marin County Public Health Department, said in a Friday phone call that once seasonal flu cases begin they continue to ramp up for the season.
“Once it starts, it’s game on,” he said. “… There’s not a lot of examples of, like, a surge and then a resolution and then another surge.”
Willis said that while the flu returns to the Northern Hemisphere every fall and winter, there’s no clear reason why it arrives in certain regions earlier than others. He pointed out that much of the country currently has very little flu activity, according to the latest data from the Centers for Disease Control and Prevention.
“I think this is an area where, you know, we need to be humble,” he said of what sparks flu season. “… It almost disappears in the summer, and then every year, reliably, it’s like the leaves turning, it just comes back.”
Willis said an early start to the season could mean that flu season this year will end earlier than in other years, or that it could last through the spring, potentially leading to more cases overall.
In addition to flu, COVID-19 has been circulating at high levels in the Bay Area for weeks, although in recent days signs point to dropping cases. Willis said this virus double-whammy should alert those at high risk to consider taking more precautions.
“We’re going be in that interval where we’re seeing both actively circulating for a good few weeks,” he said.
Gandhi said people who get sick with the flu should talk to their provider about potentially getting antiviral treatment, and that anyone with trouble breathing or shortness of breath should seek medical care right away.
Both Gandhi and Willis said the best way to protect yourself or your children is to get the flu vaccine. Virtually everyone over the age of six months is eligible for the shot. This year, a new mRNA flu vaccine is available for the first time, and works similar to how COVID-19 vaccines function.
But Willis stressed, “Get whatever shot you can, the shot that you can get is the best shot for you.”
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This article originally published at ‘Game on’: Bay Area now epicenter of California flu cases.