Flu Cases on the Rise in Sonoma County and Doctors Concerned

Dr. Gary Green has been an infectious disease specialist for 25 years. In that quarter century, he had never seen an increase in flu at this time of year, until now.

But it’s not just the strange, unseasonal rise in flu that worries Green, a doctor at Sutter Health. The particular strain driving this increase is proving to be highly resistant to the 2021-22 influenza vaccine. It comes during a period of high COVID transmission. And there is no clear picture of when either virus will peak.

Green was alarmed enough to send an alert this week to other Sutter doctors, advising them to be on their guard.

“I want to let our doctors know, in case they want to do any augmentation plans,” he told The Press Democrat. “It’s like in the ocean, when you have sleeper waves. If you have two waves hitting at the same time, it’s not good. I’m afraid this could be a sleeper wave.”

The California Department of Public Health distributed a similar health advisory on Tuesday.

The strange timing of this surge in the H3N2 virus, one of two forms of Influenza A, the other being H1N1, continues a pattern that emerged during the coronavirus pandemic. Communicable disease outbreaks have become more difficult to predict.

A similar change occurred in 2021 with respiratory syncytial virus, according to Dr. John Swartzberg, emeritus professor of infectious diseases and vaccinology at the University of California, Berkeley, School of Public Health.

“That’s mostly a childhood condition, but older people can get it too, and it can be very serious when they do,” Swartzberg said. “RSV is typically a fall virus, but last year it came in late spring, early summer. One of the phenomena that we have seen with this pandemic has changed the epidemiology of other diseases. The seasonality is changing.”

Within the Sutter Health system, Green said, it’s considered “flu season” any time more than 10% of all nasal and oral swabs test positive for the flu. That season typically arrives in November, peaks in late January or early February, and comes out of its “epidemic” phase in late March.

“It’s kind of an endemic disease in the summer or early fall,” Green added.

Except 2022 is breaking the mold. Instead of the sporadic cases of Influenza A that Sutter would normally see this time of year, “like maybe 0.1% of our swabs,” Green said, the supplier is finding positive rates closer to 15% in the Bay Area. The numbers are reportedly higher than those in the San Joaquin Valley, a fact CDPH alluded to in its advisory.

The current rate of flu in Sonoma County is undetermined. Unlike the coronavirus, influenza is not a reportable condition unless a person is hospitalized and younger than 65, according to Lucinda Gardner, an epidemiologist with the county Department of Health Services.

No one has shown any direct causal link for the current spike in influenza A, but experts seem to agree that it is related to behavioral change during the COVID pandemic.

The winter of 2020-21 saw a “remarkably low incidence” of the flu, Swartzberg said, because “the things that prevent COVID also prevent influenza.”

In other words, more people got the flu shot that year because they were scared of the new respiratory disease that had swept the planet. Many masked up and socially distanced. Schools and churches stopped meeting in person.

A year later, Swartzberg said, health care workers worried that the 2021-22 season would explode with flu cases, especially if people let their guard down. Because so few had caught the flu the previous winter, immunity would be low. Then the omicron COVID variant exploded and most people tightened their security protocols again.

“But as omicron eased and the government lifted many mask mandates, our population began to behave as if there was no longer a pandemic,” Swartzberg said. “Not only has Omicron come back with a different variant, but we’re seeing influenza that we would have seen earlier this year.”

To make matters worse, the resistance that the H3N2 virus is showing to the current flu vaccine.

Every year, Green said, doctors from the World Health Organization, the US Centers for Disease Control and other major health organizations formulate a specific flu vaccine based on the latest research. It is meant to be effective against both types of influenza A and both types of influenza B, but it doesn’t always work that way.

“It’s really unpredictable,” Green said. “Probably every one to four years, one of the strains doesn’t match the vaccine. And sometimes it’s not the predominant variety, so you barely notice it. This year, it’s kind of a perfect storm, where the dominant strain is the one that’s not affected much by the vaccine.”

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