Could coronavirus cause a better flu season? Maybe. Here's why.

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Flu season is approaching, but some medical experts say it’s possible this year’s may shape up to be milder than initially feared. The unlikely reason? The coronavirus pandemic.

As people in many parts of the country protect themselves from COVID-19 by wearing face masks, constantly washing and sanitizing their hands, and avoiding school, concerts and other types of indoor gatherings, they’re also inadvertently protecting themselves from influenza.

“I think that it is certainly possible that we’ll see a lighter flu season than usual, because people are hopefully taking a lot of precautions to prevent the spread of respiratory viruses at large — so that includes flu as well as COVID,” said Dr. Allison Bond, an infectious disease and hospital medicine doctor at UCSF.

If this year’s flu season is mild, it will be a relief to doctors who have been bracing for the dreaded overlap of influenza and coronavirus. Fewer flu cases mean more hospital staff, beds and equipment will be available for COVID-19 patients.

But experts caution it’s too soon to tell which way the 2020 flu season will pan out — and it’s still critical to get vaccinated.

“These precautions help,” Bond said of mask-wearing and hand-washing, “but they’re not foolproof. And certainly, even people who are doing everything right are still getting COVID, so obviously the measures aren’t perfect. So that’s why it’s still important that everyone get the flu shot.”

California has seen more than 770,000 COVID-19 infections and more than 14,700 deaths so far, according to this news organization’s analysis of county-reported data. That includes more than 98,000 infections and more than 1,300 deaths in the Bay Area. In 2018, nearly 7,000 people died of the flu or pneumonia in California, according to the most recent state-by-state information available from the Centers for Disease Control and Prevention.

Every year, experts in the Northern Hemisphere look toward the Southern Hemisphere — where winter arrives during our summer — for clues as to which influenza viruses will make an appearance and how bad they will be. This year, flu season was mild in the southern half of the globe.

Western Pacific Region nations, in particular, reported lower numbers of cases to the FluNet monitoring system this year compared with previous years.

In Australia, for instance, the flu season started with 6,962 cases in January and 7,161 cases in February — but fell to only 229 in April, compared with 18,705 in April last year, as the nation shut its borders, banned large gatherings and closed on-campus education.

“If one looks at the flu as it has occurred in the Southern Hemisphere, it turned out not to be as bad as many past flus, in terms of how virulent it was and how transmittable it was,” Dr. Barry Bloom, a professor in the Harvard T.H. Chan School of Public Health in Boston, said during a press briefing earlier this week.

Experts say it’s logical to think COVID precautions helped cut the number of flu cases. Both viral respiratory infections spread the same way — through droplets expelled when people talk, cough or sneeze.

“But the reality is, we don’t know what to expect,” cautioned Dr. Arthur Reingold, division head of epidemiology and biostatistics at UC Berkeley. “We don’t know which viruses for sure are going to be circulating and how invasive they’ll be or how much illness they’ll cause.”

There’s no guarantee the U.S. will follow in the footsteps of countries in the Southern Hemisphere. Mask-wearing and social-distancing practices differ greatly state by state and even county by county. Plus, rules may continue to ease up this fall and winter if coronavirus cases don’t spike, allowing schools or other gathering places to reopen.

Even in a normal year, the flu is a serious health concern — last year, there were an estimated 39 to 56 million cases in the U.S., and as many as 62,000 deaths.

“Adding that on top of COVID and an already overwhelmed health care system is worrying,” Lelia Chaisson, assistant professor of medicine at the University of Illinois at Chicago Division of Infectious Diseases, wrote in an email.

Little is known about what happens to patients who contract both COVID-19 and the flu, Chaisson pointed out. And, as both viruses present with similar symptoms, differentiating between the two may present a challenge to health care workers.

Across the board, experts are urging people to get flu shots

The Centers for Disease Control and Prevention recommend nearly everyone 6 months of age and older get vaccinated. Santa Clara County is offering free flu shots

Last year, flu vaccination rates in the U.S. were about 45%, said Howard Koh, a professor at the Harvard T.H. Chan School of Public Health, and a former assistant secretary for health under President Barack Obama.

“It would be tremendous if we, as a country, could show that we can get the seasonal flu vaccine rates way over 45%,” he said. “It would demonstrate confidence in the whole effort — and give us momentum going into the COVID vaccine effort that’s going to follow, hopefully, shortly afterward.”

Staff writer Fiona Kelliher contributed to this report.

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©2020 The Mercury News (San Jose, Calif.)