The availability of antiviral medications for both influenza and COVID-19 highlights the need to determine which virus a patient may have so that, if needed, they can be treated early in the course of illness. Nucleic acid amplification testing is a valuable tool in discriminating between influenza and COVID-19.

We are back to the prepandemic epidemiology of influenza, meaning that we are expecting the seasonal influenza activity that occurs every wintertime, usually beginning in late fall or early winter in the United States. Conversely, COVID-19 does not necessarily follow a similar seasonal pattern. We have seen increased COVID-19 activity during the summer and fall, so we do expect that there will be some overlap in the circulation of influenza and COVID-19, especially as new COVID-19 variants continue to emerge.

The populations that are affected by the 2 viruses are very similar, and both viruses also have similar clinical presentations (ie, not only a runny nose, sore throat, and congestion like other minor viral illnesses but often also more serious and systemic symptoms such as cough, body aches, chills, headaches, and fever). Further, although COVID-19 is sometimes associated with a loss of taste and/or smell, overall, it can be challenging to distinguish between influenza and COVID-19 infections simply based on the early presenting signs and symptoms.

Fortunately, testing for COVID-19 has become relatively easy to do, which is important given the overlap in the circulation of these viruses. Since treatments for both influenza and COVID-19 are now available for certain patients, testing is important for the prompt initiation of the correct treatment, especially in high-risk populations. We need to encourage everyone to keep testing for influenza and COVID-19 in mind when symptoms emerge so that they can seek treatment as early as possible. This is because antivirals work best early in the course of the illness for both viruses. Testing is also important because, if a person knows that they are infected with influenza or COVID-19, they can take precautions to help minimize the exposure of other people to these viruses.

Much of the point-of-care testing that is happening now in Emergency Department, urgent care, and, certainly, hospital settings is based on nucleic acid amplification by polymerase chain reaction, or PCR. However, having home testing has allowed families to make decisions regarding their own care and decisions regarding what to do with others around them. The ability to test at home and know that there are actions to take stemming from a positive test result has been a significant change. Your medical provider may still want to bring in infants, younger children, or certain children who might have underlying conditions, just as some examples, for a more complete evaluation before calling in a prescription for an antiviral.

In my practice, and especially in the Emergency Department, we do a lot of combined testing for influenza, COVID-19, and respiratory syncytial virus (RSV). Keep in mind, I am a pediatric provider in infectious diseases offering very specialized care, so I treat immunocompromised patients, transplant patients, and children who may need to be hospitalized. Unfortunately, some of these children (ie, those with high-risk conditions and those who are immunocompromised) tend to be among the first patients we see early in the season when they become infected with these viruses. They need to be tested and diagnosed as early as possible so that they can be treated accordingly.

Another important consideration with both influenza and COVID-19 is that vaccination rates have been low and perhaps late, in the sense that the updated COVID-19 vaccine is now available but a lot of people still have not received it. Regarding influenza, this is the time of year when most people should become vaccinated, before the season is in full swing, but the uptake for influenza vaccines also appears to be low.

RSV is another respiratory virus that often circulates seasonally and therefore may overlap clinically with influenza and COVID-19. Now that we have better virus surveillance, we are doing more testing that includes RSV in addition to influenza and COVID-19. This is going to be, again, a triple epidemic, as it has been called, and we should expect to see these 3 viruses returning every winter.