If you go to see a doctor with flu-like symptoms during this flu season, you are likely to get a swab for two tests: one for the flu and one for COVID-19. Unlike flu seasons, when there is no pandemic, doctors cannot be sure that someone with body aches and fever has the flu. This will change the diagnostic process for both diseases.
“This year, if it looks and smells like the flu, it could be the flu – or it could be COVID-19,” said Richard Webby, an infectious disease researcher at St. Jude Children’s Research Hospital in Memphis.
Sorting from each other is important. The methods of treatment may not be so different: someone with a mild case of the flu and someone with a mild case of COVID-1
“We’d like to get rid of both, but it’s the coronavirus that we’re really trying to control,” Webby said. “We want to get this person out of circulation as soon as possible.”
Doctors regularly use rapid flu tests in their offices, and the results return within 15 minutes, says Anthony Bafo-Bonnie, head of infectious diseases at the Carrilion Clinic in Virginia. The flu season has not yet intensified, so for now, the first step in treating any patient with respiratory symptoms will be to be tested for COVID-19. Once flu tests start to return positively to his area, and when flu surveillance systems start reporting that the virus is circulating, he says he will start adding flu tests.
There are several tests available that can test both influenza and COVID-19: health companies Roche and Cepheid have food and drug administration permits for joint tests, and the Centers for Disease Control and Prevention has public health laboratories. That’s the best approach, says Bafo-Bonnie. But they may not be available in every area and in every hospital – in most places you may have to rely on two separate tests.
Currently, joint tests are genetic tests: they look for fragments of the flu genetic sequence and fragments of the genetic sequence of the coronavirus. These types of tests require more specialized machines. The standard ambulatory flu test is usually an antigen test that looks for proteins that protrude from the outside of the flu virus. These tests work quickly and can produce results in about 15 minutes, but are less accurate than genetic tests. Both options are also available for COVID-19 tests.
If a joint test is not available, influenza and COVID-19 testing may mean a combination of test types. One can get a fast flu test, but a slower, gene-based test for COVID-19. The doctor may decide to send genetic tests for both viruses to a laboratory, which can be reversed in a few days. People can go to a COVID-19 test site for a quick test and go to a doctor for a flu test if that turns out to be negative.
Bafo-Bonnie says his clinic plans to start with genetic testing for viruses, while having some ability to do faster antigen testing if necessary, too.
All of these tests could help patients cope better – but it can also be very expensive, says Edward Belonia, director of the Center for Clinical Epidemiology and Public Health at the Marshfield Research Institute in Wisconsin. According to the CARES Act, adopted in the United States at the beginning of the pandemic, tests for COVID-19 must be free of charge for patients. “That’s not true of the flu,” he said. In March and April, some people with what they thought were COVID-19 were charged thousands of dollars for testing for other respiratory viruses, such as the flu.
“We don’t want people to be discouraged from coming in and getting tested because they’re worried about the cost of lab tests,” Belonia said.
This is a particular concern, as increased testing – and all the costs associated with it – may not be limited to this flu season. There is still a chance that even after the pandemic, the coronavirus will continue to circulate among the population every year. If that happens, some of the adjustments in the way doctors diagnose the flu may be more permanent, Webby said. Influenza will not be the only culprit for a feverish patient – they will have to consider other viruses.
“I think that would put pressure [the] system to change not only the flu in particular, but also the entire pipeline for testing for respiratory viruses, ”he said.