Dr. Gary Green has been an infectious disease specialist for 25 years. In that quarter century, he has never seen the flu on the rise this time of year — until now.
But it isn’t just the strange, unseasonal rise in influenza that has Green, a Sutter Health physician, concerned. The particular strain driving this spike is proving highly resistant to the 2021-22 flu vaccine. It’s coming during a period of high COVID transmission. And there is no clear picture on when either of the two viruses will peak.
Green was sufficiently alarmed that he sent out an alert this week to other Sutter physicians, advising them to be on guard.
“I want to give our doctors a heads-up, in case they want to do any surge planning,” he told The Press Democrat. “It’s like in the ocean, when you have sleeper waves. If you get 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 Tuesday.
The bizarre timing of this surge in the H3N2 virus — one of the two forms of Influenza A, the other being H1N1 — continues a pattern that has emerged during the coronavirus pandemic. It has become harder to predict outbreaks of communicable diseases.
A similar shift occurred in 2021 with respiratory syncytial virus, according to Dr. John Swartzberg, a professor emeritus of infectious diseases and vaccinology at the University of California, Berkeley School of Public Health.
“That’s primarily a condition of childhood, 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 we’ve seen with this pandemic, it’s changed the epidemiology of other diseases. It’s changing the seasonality.”
Within the Sutter Health system, Green said, it’s considered “flu season” anytime more than 10% of all nasal and oral swabs come up positive for influenza. That season usually arrives in November, peaks in late January or early February and exits its “epidemic” phase by late March.
“It’s just sort of an endemic disease in summer or early fall,” Green added.
Except 2022 is breaking the mold. Instead of the sporadic cases of Influenza A that Sutter would typically be seeing this time of year — “like maybe 0.1% of our swabs,” Green said — the provider is finding positive rates of closer to 15% in the Bay Area. The numbers are reportedly higher than that in the San Joaquin Valley, a fact the CDPH alluded to in its advisory.
The current flu rate in Sonoma County is undetermined. Unlike the coronavirus, influenza isn’t a reportable condition unless a person is hospitalized and under the age of 65, according to Lucinda Gardner, an epidemiologist in the county’s Department of Health Services.
No one has proved any direct causal links for the current spike in Influenza A, but experts seem to agree it is related to changing behavior during the COVID pandemic.
The winter of 2020-21 saw “remarkably low incidence” of flu, Swartzberg said, because “the things that prevent COVID also prevent influenza.”
In other words, more people got their flu shots that year because they were freaked out about the new respiratory disease that had swept the planet. Many were masking and social distancing. Schools and churches stopped meeting in person.
A year later, Swartzberg said, health workers worried the 2021-22 season would explode with flu cases, especially if people let down their guard. Because so few had gotten the flu the previous winter, immunity would be down. Then the omicron COVID variant blew up, and most people tightened up their safety protocols again.
“But as omicron abated and the government got rid of a lot of mask mandates, our population started behaving like there was no pandemic anymore,” Swartzberg said. “Not only has omicron come back with a different variant, but we’re seeing the influenza we would have seen earlier this year.”
Making matters worse is the resistance the H3N2 virus is showing to the current flu vaccine.
Every year, Green said, doctors with the World Health Organization, the U.S. Centers for Disease Control and other major health organizations formulate a specific flu shot based on the latest research. It’s meant to be effective against both types of Influenza A and both types of Influenza B, but it doesn’t always work out that way.
“It’s really hit and miss,” Green said. “Probably every one to four years, one of the strains doesn’t match the vaccine. And sometimes it’s not the predominate strain, so you hardly notice it. This year, it’s sort of a perfect storm, where the strain that’s dominant is the one that isn’t affected much by the vaccine.”