With fall comes the onset of flu (influenza) season, but because many of the symptoms of Covid-19 and flu are similar, you may need to be tested to find out which you may have (and yes, you can be infected with both at the same time). The CDC has a useful table of similarities and differences between Covid-19 and flu.
Here are some key facts to know.
Going viral
Covid-19 and flu are both contagious respiratory illnesses, but they are caused by different viruses: Covid by the novel coronavirus called SARS-CoV-2, and flu by influenza A and B (and sometimes C) viruses. Common symptoms of both include fever, chills, coughing, shortness of breath or difficulty breathing, fatigue, sore throat, runny or stuffy nose, muscle pain or body aches, and headache.
Both illnesses can cause anywhere from mild (or no) symptoms to severe ones, and they have many of the same potential complications, such as pneumonia, respiratory failure, heart attacks, strokes, and death. Older adults and people with underlying medical conditions are at highest risk for serious complications. Both flu and Covid can be spread by people with no symptoms (asymptomatic transmission).
Some important differences between the illnesses have emerged, however. Covid, for example, is less likely than flu to cause severe disease in healthy young children (though it certainly can), and it is deadlier for adults than flu. Other distinguishing Covid-19 characteristics include:
- Loss of smell or taste, or other unusual symptoms. Loss of smell or taste without nasal congestion is a symptom of Covid but not of flu. Covid has also been associated with some other seemingly incongruous symptoms, most notably neurological changes, such as confusion and impaired consciousness.
- A longer incubation period. Flu symptoms typically start one to four days after exposure. Covid also appears to be contagious for longer—and the Delta variant even more so—regardless of whether or not symptoms are present.
- “Super-spreader” capacity. Covid and flu are thought to spread in similar ways—mainly through respiratory droplets that pass from person to person within roughly six feet, and that are emitted through coughing, sneezing, or talking. But Covid has been associated with more “super-spreading” events, in which the virus quickly and easily spreads to a lot of people, often at considerable distance from each other. This is all the more reason for everyone to avoid large gatherings now, especially indoors.
- Blood clotting effects. In addition to the complications it shares with flu, Covid increases the risk of blood clots in the veins and arteries of the heart, lungs, legs, and brain. This may help explain why cerebrovascular events, mainly strokes, have occurred in many Covid patients. And it probably contributes to Covid’s higher fatality rate.
- No widely available approved treatment, yet. The antiviral drug remdesivir received FDA approval in October 2020 for treating patients (both adults and children over age 12) hospitalized with Covid. But there are still no antiviral drugs approved for treating unhospitalized people with Covid, as there are for the flu.
What to do: Get a flu shot, get a flu shot, get a flu shot. In a “normal” year, it not only cuts your risk of getting infected with influenza but can make the illness less severe if you do get it—which in turn lowers your risk of developing complications and of spreading the illness to others.
But there’s another reason to get the vaccine: It can help reduce the overall impact of respiratory illnesses on the population and thus lessen the burden on our already strained health care system during the pandemic. Note that if you have a suspected or confirmed case of Covid, you must wait until your recommended isolation period is over before getting your flu shot.
In addition, continue to follow public health recommendations for physical distancing, mask wearing, cleaning and sanitizing, and handwashing for as long as Covid is circulating, and encourage others to do the same. These steps will help protect you from flu (and colds) this year, too.
A small piece of good news is that last year there was barely a “flu season” because of all the protective measures that were in place for Covid. Hopefully that will be the case again this round.
