The Perfect Enemy | As California braces for severe flu season, doctors urge shots — with or without a COVID booster
April 18, 2024

As California braces for severe flu season, doctors urge shots — with or without a COVID booster

As California braces for severe flu season, doctors urge shots — with or without a COVID booster  San Francisco ChronicleView Full Coverage on Google News

It’s more critical than ever to get a flu shot this year, say Bay Area infectious disease experts. Two-plus years of the COVID-19 pandemic have created conditions — including lower influenza vaccination rates and less natural immunity than in the pre-pandemic period — that could make the upcoming flu season one of the worst in recent years.

Influenza vaccination rates in California and nationwide dipped for the 2020 to 2021 flu season compared with 2019 to 2020, which experts attribute in part to COVID lockdowns or because many people delayed nonemergency medical visits, including some vaccinations. Meanwhile, widespread COVID masking, which was mandatory in most Bay Area public spaces in 2020 and most of 2021, tamped down overall levels of flu transmission — which means fewer people now have some recent natural immunity.

“Those last couple years did not have a lot of flu,” said Dr. Jeffrey Silvers, medical director of pharmacy and infection control at Sutter Health. “Last season, we had some, but we can anticipate there’s a real possibility we could have a significant flu season this year and that it may be bigger than what we’re used to.”

Silvers’ take-home message: “People should get vaccinated this year. It’s very important and I’d say it’s more important than it’s been in the last few years to be prepared.”

Adding to the urgency are reports from countries in the Southern Hemisphere, whose earlier flu seasons often provide clues about what lies ahead for the North. Many are reporting more severe influenza outbreaks than usual: Australia, for instance, just saw its worst flu season in five years, with cases peaking at about three times higher than average. The cases also happened roughly two months earlier than usual, according to data published in August in the medical journal the Lancet Infectious Diseases.

“That often bodes a little bit worse for us if their season is more serious,” said Dr. Darvin Scott Smith, an infectious diseases doctor and clinical vaccine lead for Kaiser Permanente Northern California.

The good news, Silvers said, is that this year’s flu vaccine is better matched than last year’s to the primary strain circulating around the world, H3N2, and the few others that are emerging in some areas.

And those 65 years and older — the group most vulnerable to severe disease and death from flu and COVID — can get an “enhanced” flu shot that provides more protection than the regular shot. While enhanced versions, which either contain a higher dose than the regular shot or elements that boost immune response, have been available in previous years, the U.S. Centers for Disease Control and Prevention is for the first time recommending them for all Americans 65 and older.

In California, overall flu vaccination rates fell slightly from 51% in 2019 to 2020, the most recent pre-pandemic flu season, to 49% in 2020 to 2021, according to figures from the U.S. Centers for Disease Control and Prevention. Nationwide, flu vaccination rates fell more, from 64% to 59%, when comparing the same periods. Data for the 2021 to 2022 flu season is not yet available. Flu shot uptake generally ranges from 40% to 60% most years.

Flu season in the U.S. typically runs from October until February, and this year’s is poised to follow a similar timeline.

In a new wrinkle, the availability of the flu vaccine this year coincides with the majority of Americans becoming eligible for the new COVID booster shot. Experts say it’s reasonable — though not necessary — to get a flu shot and COVID booster at the same time for the sake of convenience and efficiency. But doing both at once may not make sense for everyone, since the timing of the COVID booster depends on when someone got the previous COVID shot or infection, plus some wiggle room for personal risk appetite and behavior.

“You can get the influenza vaccine and COVID booster at the same time and that’s very reasonable and it’s a good idea, but if people want to space it out there’s nothing wrong with that,” said Sutter Health’s Silvers. “Whatever works for you. … Studies show if you get the booster for COVID and the flu shot at the same time, soreness and reaction to vaccination is not much different than just getting the COVID booster alone.”

For most people, getting the flu shot around the end of September or in October is ideal — generally by November is best, experts say. The exception, Silvers said, is pregnant women in their third trimester who should get it sooner rather than later — at least two weeks before delivery so antibodies will pass over to the newborn because otherwise infants aren’t eligible for flu shots until they are 6 months old.

The timing, with both shots becoming available at the same time, is also raising questions about whether COVID fatigue — pandemic fatigue overall, or vaccine fatigue specifically — may contribute to lower uptake of the flu shot.

“That is a challenge,” Silvers said. “Our fatigue from hearing about COVID, dealing with COVID, hearing about flu shots, and receiving immunizations in general is an important concern that I have.”

Anecdotally, that does not appear to be the case but because flu vaccinations are just starting, it’s too early yet to know about uptake. At UCSF’s drive-thru and walk-in vaccine clinics in San Francisco, at least, demand for the flu shot has been higher these last few weeks than normal, said Desi Kotis, UCSF’s chief pharmacy executive. At clinics in Laurel Heights and Mission Bay, people are coming in for their COVID booster and getting their flu shot at the same time, she said.

“I imagine we’ll have a fair number of people on the fence,” said Sutter’s Silvers. “Hopefully before (flu) hits us locally, it will be showing up in other places and the news will start reporting where influenza outbreaks are starting to occur so people understand it affects them and they have to get ready.”

Catherine Ho (she/her) is a San Francisco Chronicle staff writer. Email: Twitter: @Cat_Ho