As we enter cold and flu season, here's how to tell if you have COVID or a cold

As we lurch into fall and then winter, we also say hello to flu season, which starts in early to mid-September.

But we are also in the throes of a pandemic, and when we come down with sore throats and runny noses, how do we tell if it's COVID-19 or something else?

The short answer is that there's no rule, according to Dr. Mary Hayden, a professor at Rush University and head of the university's Division of Infectious Diseases. The symptoms are so similar that "there's really nothing that clearly differentiates one illness from the other," making it nearly impossible to reliably self-diagnose.

But here are some quick tips from experts for when you're wondering whether you have COVID-19, and that could help you protect yourself and the people around you.

Watch for symptoms, such as loss of smell, that don't match up with common illnesses.

Loss of smell is a symptom that is "more suggestive of COVID," said Hayden, "especially if you don't have nasal congestion."

People with COVID-19 may lose their sense of smell without getting any of the other cold symptoms such as a sore throat or blocked nose, which is a "clue," said Hayden.

This loss of smell is also different from when you get a blocked nose and can't smell anything, or breathe properly. People with COVID-19 also get dysosmia, which is where "everything you taste tastes terrible," said Aniruddha Hazra, assistant professor in the University of Chicago Medicine's Section of Infectious Diseases and Global Health.

Websites offer lengthy checklists of symptoms that fit more with specific illnesses. This helps you identify symptoms that don't square with conditions you typically get. For example, if you have a fever, said Hayden, this should rule out allergies because people with allergies don't typically run a higher temperature.

Decide when to get tested, and how to choose the right test.

There are two different tests: Rapid antigen tests, which were popular during the beginning of the pandemic, and polymerase chain reaction tests, called PCR tests.

PCR tests are "the gold standard," said Hazra, because they're much more sensitive, working by picking up genetic material specific to COVID-19 with the ability to detect "tiniest traces" of the virus.

But this doesn't mean that rapid tests don't have their uses. It depends on the situation, said Hazra. Even if a test isn't perfect, "this doesn't mean it can't be used in an educated way," he said.

Despite being more reliable, PCR tests are slower than rapid tests, taking 24 to 48 hours to provide results. So if you need answers in a matter of minutes, rapid antigen tests are your best call. You can use these if you have symptoms and you're trying to decide whether you should go to work, or to see your grandma, said Hayden.

These tests are actually "comparable to PCR tests" when you have symptoms, added Hazra. But if you're worried you have asymptomatic COVID-19 after you've been exposed to someone with a confirmed case, or you've been to a big event and are concerned that you got the virus, you should take a PCR test. Rapid tests often don't pick up on asymptomatic cases, which could lead to a false negative test result.

"The best way to give yourself peace of mind is to get tested five days after exposure if you have no symptoms," said Hazra.

You can go to a testing center or to your doctor for a PCR test, said Hazra. The rapid tests most available in the U.S. are BinaxNOW tests by health care company Abbott Laboratories.

But there is a cost barrier to these tests in the U.S. that isn't found in Europe, said Hazra. In Denmark, a rapid test is available for the equivalent of $3, whereas in America a pack of two tests costs more than $20.

"There's still obviously an access issue," said Hazra, particularly for communities hit the hardest by COVID-19, which are often working-class and may not be able to afford home tests.

The test "has to be accessible for it to really make a difference," said Hazra.

Weigh your specific circumstances.

For people who are vaccinated, said Hazra, the vaccine should give them some "peace of mind," because the likelihood of getting sick is small, and people who do have breakthrough infections will experience a milder form of the virus.

But you should think about why you're getting tested, according to Hayden. If you work from home and never go out, you don't need to worry about getting tested, she said. But if you're in contact with other people, especially those who are immunocompromised or not vaccinated, you should get tested regardless of your vaccination status.

People who are immunocompromised also could be subject to specific caveats and complexities, said Hayden. Small studies have shown that some people who have kidney transplants, for example, have not developed antibodies after two, or even three vaccine doses.

These are people who could be particularly affected by those who transmit the disease. We need to think about the "chains of transmission," Hayden said.

If you have the virus, you might "expose someone who got a little sick, who then exposes someone else who got really sick," said Hayden.

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