As influenza season approaches, some Americans, and especially parents, are worried that, if they or their children should become ill, it may not be easy to know which disease they have — the flu or Covid-19.
They are correct. Most symptoms of the two diseases are so similar that, short of a test — or two or three tests — it won’t be possible to know for sure. But there are some clues. (And it is possible to have both infections at the same time; some patients in China this year were found to have both.)
But first: get a flu shot.
It is not yet clear whether the United States will have much of a flu season this year. Flu activity in the Southern Hemisphere, which is often predictive of activity in the United States, was 99 percent below normal during its winter. Epidemiologists believe that is because Australians, New Zealanders, South Africans, Chileans and other residents of the southern half of the globe were wearing masks, staying several feet apart and washing their hands to prevent transmission of the coronavirus. Those same precautions also prevent flu transmission.
Because there are very few flights between the Southern Hemisphere and the United States right now, there may be no opportunity for the usual four seasonal influenza strains to “reseed” themselves among Americans. If they do, masks and social distancing should limit their spread.
Assessing the difference between a cold and the flu.
There are at least 100 viruses that can cause the common cold, but only four that cause seasonal flu. Many people who catch colds assume they have the flu, but experts consistently say the same thing about how to tell the difference: “Flu makes you feel as if you were hit by a truck.” The fever, aches and headaches of a bad case of influenza are generally worse than a case of respiratory syncytial virus, rhinovirus or other common cold viruses.
Everyone knows the symptoms of the flu: fever, headaches, body aches, sore throat, runny nose, stuffed sinuses, coughing and sneezing — and, for infants, ear infections. Some victims, especially children, get diarrhea or vomiting too.
In severe cases, the most common complication is pneumonia. The typical signs of a flu pneumonia are shortness of breath, especially when you exert yourself, and unusually rapid breathing — doctors typically look for that in children — and sometimes pain in the chest or back.
Identifying Covid-19 by its flulike and ‘wacky’ symptoms.
Knowing whether you have Covid-19 is much more complicated because there are so many different — and sometimes pretty wacky — symptoms, many of which echo those of the flu.
The one sign that really distinguishes the two infections is that many Covid-19 victims suddenly lose their sense of smell — not because they have a stuffy nose, but because they don’t register even strong odors like onions or coffee. Not all virus victims get anosmia, the formal name for loss of smell, but one study found that 87 percent did.
Less common symptoms include a sore throat, congestion, runny nose, vomiting, diarrhea, stomach pain and feeling somewhat out of breath when exerting yourself. Some victims have red or itchy eyes, and some get redness or blisters on their fingers or toes — so-called Covid toes, which resemble chilblains.