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Will flu season collide with COVID-19?

September 21, 2020 | UCI Health
Woman suffers from respiratory virus.

“So far there is no indication that there will be a new virulent flu strain this year,” says UCI Health Dr. Shruti K. Gohil, MD, “but there is no way to really know until the flu season is underway.”

So much remains unknown about how the novel coronavirus will behave in the future, but epidemiologists expect it to return this fall and, much like influenza, stick around Southern California from October through April.

That has led to speculation that a “twin-demic” may occur this fall, with patients becoming infected with the flu and COVID-19, respiratory viruses that have many symptoms in common. It's why public health officials are encouraging everyone to get flu vaccinations this year.

“It’s too early to make assumptions about the severity of this year’s flu season,” says Shruti K Gohil, MD, MPH, UCI Health associate medical director of epidemiology and infection prevention. “So far there is no indication that there will be a new virulent flu strain this year, but there is no way to really know until the flu season is underway.”

Testing needed

When people refer to a “twin-demic,” it is not so much that there would be two pandemic virus strains, but rather that these two contagious viruses are spreading at the same time.

The combination of COVID-19 and flu viruses circulating this season poses two issues:

  • First, people could become infected with both at once or in succession.
  • Second, the similarity of symptoms — fever, cough, fatigue, sore throat, headache and more — will make diagnoses difficult without testing, which may strain already overloaded health systems. 

Flu vaccination vital


Doctor administers a vaccine shot
“We’re getting flu vaccines out there,” Gohil says. “We’ve stocked up early to make sure we can get everybody vaccinated before a resurgence of COVID-19.”.

Doctors and public health officials are urging people to get influenza vaccinations this fall, not only to help prevent the spread of the flu, but also to help them assess how likely a patient may have one or the other.

For example, if a patient has been vaccinated for the flu, the likelihood is higher that their symptoms may be due to coronavirus, Gohil says.

The efficacy of flu vaccines can range from 25% to 60% in any given year. Although there’s no way yet to predict how well this year’s vaccine will perform, vaccines typically are effective at limiting deaths and hospitalizations. The U.S. Centers for Disease Control and Prevention estimates that influenza has resulted in between 140,000 to 810,000 hospitalizations and between 12,000 to 61,000 deaths annually since 2010.

Having fewer severe flu cases also would reduce the strain on hospitals when a resurgence of COVID-19 occurs during flu season.

UCI Health, which has always required its healthcare workers be vaccinated against influenza, began offering this season's flu vaccine to patients in August.

“We’re getting flu vaccines out there,” Gohil says. “We’ve stocked up early to make sure we can get everybody vaccinated before a resurgence of COVID-19.”

Ready for a second wave

UCI Health is prepared for a resurgence of COVID-19 this fall because procedures developed to handle the first wave remain firmly in place. They include:

  • Universal masking, distancing and hand hygiene throughout all facilities
  • Mandatory screening of patients, visitors and employees entering all medical locations
  • Evaluating symptoms and isolating patients suspected of being infected with the virus
  • Multiple contingency plans for handling a surge of COVID-positive patients

“When a resurgence does occur,” Gohil says, “the mechanisms we developed for the first wave of COVID-19 to keep patients safe are still in practice, so patients can feel comfortable seeing their doctors and getting care.”

Preventing flu, too

Interestingly, the same safety measures people are taking to curtail the spread of COVID-19 may result in a less severe cold and flu season.

“If people are compliant with COVID-type recommendations,” says Gohil, “I think we could see less transmission of these diseases, too.”

She also is hopeful that people have accepted masking, physical distancing and hand hygiene as effective strategies for combatting COVID-19.

 “Practice them until it’s a daily routine, just a part of your everyday life,” she says.