Home / Health / These charts show startling pictures of ‘very unusual’ Bay Area flu season.

These charts show startling pictures of ‘very unusual’ Bay Area flu season.

Until now, “influenza” and the coronavirus feared by health workers have not been able to occur.

Influenza kills tens of thousands of Americans and may require hundreds of thousands of hospitalizations in winter. But this year, it has fizzled almost entirely in the Bay Area – the stroke of windfall required as coronavirus cases, hospitalizations and deaths rise uncontrollably.

Randy Bergen, Kaiser’s pediatric infectious disease specialist who is clinical lead for the Flu Vaccine Program in Northern California, said, “Our hospital is always full during the winter and in the regular year. It’s because of influenza. This is a very unusual year. But because of the different respiratory viruses “

A typical year found that the hospital flu test rate was 20% -40%, but this year doctors didn̵

7;t really see such a case. About one in four patients who come to the hospital with respiratory symptoms are positive for the coronavirus. But three others had other diseases: not the coronavirus, not the flu, and not the respiratory syndromes, or RSV, another common respiratory virus. Which causes thousands of deaths each year in the United States. But that also fell off the map.

Dr. Gary Green, an infectious disease expert with Sutter Medical Group of the Redwoods in Santa Rosa, said doctors had seen only sporadic cases of influenza A and influenza B, with a steady increase in influenza A over a period of three. -4 weeks

The lowest flu season in the Bay Area reflects what has already been shown in the Southern Hemisphere in places like Australia, New Zealand and South Africa, where flu season passes without the flu to speak of. The same trend is reflected in the United States and in California, where this season’s flu rates are much lower than normal.

According to the Centers for Disease Control and Prevention that tracks doctor visits for flu-like symptoms, as a percentage of all visits, California has been between 1% and 2% since the season began on Day 1. October. During the past four years, that share has Be in the range anywhere from 3.5% to 6.5% at this time.

A report from the California Department of Public Health’s Influenza Surveillance Program, which tracks the flu in weekly reports, paints even more shocking images of the flu season gone off radar.

Take, for example, the first week of January, which is halfway through the flu season, when patients and hospitalizations often peak in the 2019-20 week season, the flu epidemic has spread across the state, with More than 26.9% had tested positive for influenza in the laboratory, 19 pandemics, and 70 deaths that season up to that point. Hospitalization was higher than expected.

The 2020-21 report looked no more different, with 0% flu exposure in hospitals, a 0.3% positive lab flu test rate, and no outbreaks since the fall. Seven deaths have been reported, but a California map shows virtually no flu activity in the state.

So what happened?

So far, some experts have linked this year’s quieter season with the release of an effective flu vaccine that has allowed people to get a lot of vaccinations, some for the first time, and much faster than Lawrence Drew usually. Retired virology, who heads UCSF’s Clinical Virology Laboratory.

“The best we’ve seen in the United States for a vaccine collaboration is 50-60%, and that’s not enough to explain, and it can’t explain RSV,” he said.

Drew said some people have defined a quiet season as a concept known as viral infestation when one viral organism resists being infected with a second virus. But it seems very unlikely, he said, because they’re typically associated with similar viruses and influenza, SARS COV-2 and RSV are not the same.

What is the closest explanation, Drew and other experts say, is that pandemic public health measures of masking and social aloofness are far more effective in preventing the spread of influenza and RSV – more than just a pandemic. Spread of the corona virus

There’s a scientific basis for that: Studies have shown that SARS COV-2 is more infectious than seasonal major respiratory viruses, including influenza and RSV. The new coronavirus, which has arrived in the United States and California, is contagious. Some numbers point to a 70% increase in transmission.

Influenza activity across the country was abnormally low, according to the CDC this season. Although California now has a higher rate of flu-like illness than the country. But such a sharp rise is not uncommon in flu season. It could also be linked to an increase in people with coronavirus in the state, mostly in Southern California, where officials said, partly due to more lax compliance with public health guidelines. (At this time of last year and at the start of the current flu season, the California average is lower than the national average.)

At the end of December, doctor visits for patients with flu-like symptoms in California accounted for 2.3% of all visits, while the nation’s rate was 1.6% Drew suspected the Bay Area might. It does better than other parts of states and countries that may not adhere to as strict public health guidelines.

Bergen, a Kaiser pediatric infectious disease expert, said flu season always starts in schools and that most schools in the Bay Area are distant or hybrids with masks. Wear and social aloof

The launch of the coronavirus vaccine in California and the United States started slowly, and the long year of COVID-19 is likely several months away to be out of control. And flu season doesn’t always peak in December or January, Bergen said, so if people stop wearing masks, socialize and follow hand hygiene, the two diseases are still on the horizon.

Drew’s long view is even more urgent. If people come out of this flu season and get closer to the next, as if this never happened – avoiding concealment, social aloofness, and so on, all that security will reverse. The guidelines that helped us avoid the common cold this year are crucial to continue.

“Two years from now – five or 10, or maybe just one time – we’re going to have an influenza pandemic,” Drew said, adding that strains are likely to happen where scientists won’t have a vaccine. “Everyone knows … there is no question about it, we owe it”

Annie Vainshtein is a staff writer for the San Francisco Chronicle team. Email: avainshtein@sfchronicle.com Twitter: @annievain.

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