Bay Area hospitals have reported their first cases of influenza, signaling the start of what could be a turbulent flu season with COVID-19 in the mix.
The flu season doesn’t typically begin in earnest until December or January in California, but doctors already are bracing for a worst-case scenario of widespread influenza on top of the coronavirus and other respiratory viruses that may be circulating.
Public health experts want as many people as possible to get vaccinated against influenza over the next couple of months to protect themselves and keep hospitals from being overrun. At the same time, health care providers need to expand testing for both the coronavirus and the flu in the coming weeks so they can quickly sort out who’s infected with either virus — or if people are sick with both.
It’s possible that the Bay Area may see a remarkably calm flu season if large numbers of people are vaccinated and if residents continue to wear face coverings and maintain social distancing to prevent spread of the coronavirus. The Southern Hemisphere had virtually no influenza over their winter months, suggesting that COVID-19 prevention can help stop the flu, too, according to a study released Thursday.
But if the coronavirus surges in the fall, as it did this summer, and if the coming flu season isn’t blunted by protective measures, that could be a public health nightmare, infectious disease experts warn. Hospitals could be overwhelmed, potentially leading to more serious illness and death from both diseases.
“Even a mild flu season is disastrous on top of what is already an uncontrolled pandemic,” said Dr. Charlies Chiu, head of UCSF’s infectious diseases division. “We’re not handling COVID-19 very well. A few thousand flu cases could be enough to overwhelm our hospital system.”
Kaiser Permanente, Sutter Health and other major providers began offering flu shot clinics this month and anticipate vaccinating 10% to 15% more people this year than usual. Most people are being advised to find a drive-through vaccination clinic near them, to avoid clustering in doctor offices or other indoor spaces where COVID-19 could spread.
Doctors want as many people vaccinated as possible to prevent the widespread illness that occurs in a normal flu season, and also to protect individuals from becoming co-infected with influenza and the coronavirus. There also is evidence that the flu vaccine may offer some protection against serious illness from the coronavirus, though more study is needed, said Dr. Jeffrey Silvers, medical director of infectious disease at Sutter Health in the Bay Area.
“The flu shot stimulates part of your immune system that is the same part stimulated for COVID,” Silvers said. “So you may get a second benefit from the flu shot this year. If you do get COVID, you may not get as severe disease.”
The UCSF emergency department this week reported its first case of Type A seasonal influenza, and the first Type B case was reported at an East Bay hospital last week, infectious disease experts said. The state public health department has not yet started issuing weekly flu reports as it does during the season.
Getting the vaccine
Anyone can find a flu vaccine location at vaccinefinder.org. Many pharmacies offer them at low cost or free.
Kaiser recommends that its members get vaccinated at one of its drive-through clinics. Appointments aren’t necessary, but members should make a reservation online before showing up. Clinic locations and reservations are at kp.org.
Sutter Health patients can book an appointment online at sutterhealth.org/flu.
Doctors say they typically see a handful of flu cases through the summer, so the recent reports are not cause for concern. In fact, flu reports have been lower than usual in recent months, partly because no one’s looking for it — testing resources have been diverted to the coronavirus.
Another explanation for the low numbers is that social distancing, though not effective enough to prevent a surge in COVID-19 cases over the summer, quashed the small amount of influenza that circulates in the off-season. A study released Thursday by the Centers for Disease Control and Prevention suggested that coronavirus containment efforts may have led to an early and abrupt end to the U.S. flu season in March. And flu reports during the typically slow summer months are at “historical lows,” according to the CDC.
More compelling evidence that COVID-19 control efforts can also stop the flu: Three Southern Hemisphere countries reported almost no influenza during their usual flu season, according to the CDC. Australia, Chile and South Africa, combined, reported only 51 flu cases out of 83,307 samples tested in April through July, a positive rate well below 1%. In the previous three years, the positive rate was about 14% for those three countries in that time frame.
That bodes well for California and the Bay Area, if people stick to social distancing in the fall and winter, infectious disease experts said.
“We’re really, really hopeful that universal masking will not only decrease transmission of COVID but also flu,” said Dr. Maria Raven, chief of emergency medicine at UCSF, in a panel discussion on the pandemic on Wednesday. “We’ve seen that in the Southern Hemisphere. We’re hopeful for that to happen here, but prepared for it to not happen.”
Over the next month or two testing for both influenza and the coronavirus will increase, as more respiratory illnesses begin to circulate and doctors face patients with symptoms like cough and fever that aren’t easily pinned to one disease or another.
Major providers like Kaiser are hoping to get a test soon that would let them screen for influenza and the coronavirus at the same time. The CDC developed such a test and it was approved by the Food and Drug Administration in July, but it has yet to be widely distributed.
This week, Kaiser sent out an advisory to members meant to help them distinguish between symptoms of COVID-19, influenza and common colds. But doctors noted that it’s nearly impossible to tell the difference between flu and COVID-19 without a laboratory test.
Influenza and the coronavirus both can cause fever, cough, shortness of breath and body aches; the only distinguishing factor for COVID-19 is a loss of taste and smell, but not everyone experiences that symptom. Colds are a little easier to tell apart because they don’t usually include a fever and people don’t feel nearly as awful, but they could still be confused with a mild case of COVID-19.
Last spring, when the coronavirus first began circulating widely and testing resources were slim, public health officials told people to not bother getting tested unless they were seriously ill or had contact with a known COVID-19 case. But the guidance will be different this fall, health care providers said.
To control the pandemic, everyone who may have the coronavirus should be tested right away so that their cases can be investigated. Plus, doctors will want to know right away whether someone has influenza, which can be treated with antivirals, or COVID-19, which would require more aggressive isolation protocols.
“Definitely our philosophy during this fall and winter is going to be to test very heavily,” said Randy Bergen, clinical lead for Kaiser’s flu vaccination program in Northern California. “These conditions — influenza, COVID, colds and even respiratory difficulties from smoke and allergies — have a huge degree of overlap in symptoms. And in terms of distinguishing flu from COVID, that’s really difficult.”
Erin Allday is a San Francisco Chronicle staff writer. Email: firstname.lastname@example.org Twitter: @erinallday