How to tell the difference between COVID-19 and flu?

Change of season generally brings with it a deluge of flu cases. And this year, we have the wild card of COVID-19.

Physicians say if we stick with the social distancing and mask-wearing to prevent COVID-19, those precautions could reduce spread of flu in the bargain.

But amid uneven compliance with these preventive measures, infectious-disease specialists warn that we could face a double whammy of COVID-19 and flu this winter.

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Among those urging vigilance is Jeanne Marrazzo, a director of the Infectious Diseases Society of America and a physician researcher.

“The big concern this year, of course, is that we are going to see what could be a perfect storm,” she said. “We really can’t be complacent about this.”

The difficulty is not just that flu and COVID-19 will be circulating at the same time, said John Zurlo, chief of the division of infectious diseases at Thomas Jefferson University. It is hard to tell one disease from the other.

Both illnesses can be characterised by fever, aches, and shortness of breath.

 Among the few distinguishing features between flu and COVID-19 is the sudden loss of smell. TNS

Among the few distinguishing features is the sudden loss of smell experienced by some COVID-19 patients.

Flu can impair the sense of smell, too, but in that case the culprit is a stuffy nose, whereas in COVID-19 the reason is temporary damage to olfactory cells, Zurlo said.

Another way to tell one illness from the other is laboratory testing.

Health systems plan to use “multiplex” tests that will analyse a patient’s nasal swab for evidence of both viruses.

Such tests might be used more for older patients who are at greater risk of complications from the flu, he said.

The results would help physicians determine whether to administer an antiviral drug, which can reduce the severity of flu if given soon enough.

If there are delays in testing or if supplies run short, the fallback option would be to treat any severe respiratory illness as a potential case of COVID-19, Marrazzo said.

Patients with either illness should isolate in any case, but if there is a suspicion of COVID-19, health departments may wish to notify others with whom infected people have come into contact.

And above all, get a flu shot, she said. That reduces the risk of flu for the individual and lessens the burden on the health care system.

“If there’s ever a year that you need to get your flu vaccine and get your kids vaccinated, this is the year,” she said.