COVID-19 and Flu Season

by Glenn W. Wortmann, Section Director, Infectious Diseases
October 13, 2020

Influenza (or what we commonly call flu) is one of several viruses which can infect the respiratory tract and cause symptoms of runny nose, cough, and nasal congestion (and occasionally more severe illnesses such as pneumonia, which is an infection of the lungs).  However, it’s not the only virus which can infect the respiratory tract. Many such viruses exist in the environment, including those that cause the common cold, such as our usual coronaviruses, rhinovirus, and adenovirus.

In late 2019, what we tend to call “the coronavirus” appeared in Wuhan, China, and then spread to the U.S. in March 2020. Although we have coronaviruses in the U.S., this was a new strain and was called COVID-19. This severe virus has driven a pandemic that has spurred the worldwide population to adopt face coverings and avoid contact with crowds.

Although seasonal flu can be serious, it is generally not as dangerous as COVID-19. Most people with flu will feel better after a few days. For some, the infection may move lower, into the lungs, where it can cause pneumonia. This is when flu becomes problematic, especially for the elderly or for patients with underlying medical conditions like asthma, diabetes, and heart or kidney disease.

Flu Vaccine: Your Best Defense

New flu virus strains appear each year, so every flu season is a little different. At the low end of the scale, the Centers for Disease Control and Prevention (CDC) estimates an annual 9 million flu cases and 12,000 deaths in the U.S. On the other end of the spectrum, in the winter of 2017–2018, an estimated 45 million cases killed at least 80,000 people, the most deaths from flu in over 40 years.

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As medical professionals, we recommend the flu vaccine each year. And this year, with COVID-19 still prevalent and a vaccine not yet available, the stakes are higher. Everyone who can get a flu vaccine should do so. It won’t protect you against COVID-19, but it may save your life if it prevents you from contracting common flu while you’re still at risk for COVID-19.

In general, the vaccine is recommended for everyone over six months of age. Plus, even if you are perfectly healthy, getting the vaccine helps to protect those around you, particularly if you live or work with young children or the elderly.

Now is the time to get the flu vaccine—whether by injection or nasal spray—to give your body time to build immunity to the viruses. Your healthcare provider can recommend the best way to have your vaccine administered, depending on your circumstances.

Can the Vaccine Give Me the Flu?

We can’t overstate this: it is not possible to get the flu from the vaccine.

The vaccine is carefully formulated each year to protect against specific viruses that are expected to cause health issues. Patients who receive the vaccine will have a mild reaction of soreness or fatigue for a day or two, the body’s natural response. But there is no way to contract flu from the vaccine. Its safety has been proven over decades.

The vaccine, of course, will never be 100% effective, because new viruses crop up each year after the vaccine is already manufactured. If a patient contracts flu after a flu shot, it’s likely that one of these newer viruses is to blame.

Separate and Distinct Diseases

COVID-19 is still at the forefront, causing illness and death. Fortunately, however, most who contract it do fine. Similar to seasonal flu, age is the greatest risk factor with COVID-19, along with underlying medical conditions. For young and healthy people, the death rate from the novel coronavirus is around 1%. But for patients over 70, the death rate jumps to 20%–30%.

We must not let “pandemic fatigue” set in just as the weather turns colder and people huddle indoors. If we let our guard down and stop taking precautions against COVID-19, we will likely see an uptick in cases. This has already happened in some states, as well as in Europe.

Remember: COVID-19 and annual flu are separate and distinct diseases. Having one won’t give you immunity from the other. And yes, it is possible to get both—even at the same time. This makes getting the flu shot a priority, especially if you have any underlying conditions, care for someone at risk, or work in healthcare.

Preventative Measures Work

Both COVID-19 and seasonal flu spread the same way—person to person, mostly through the air and also, to a lesser degree, on surfaces.

Findings from the Southern Hemisphere, where flu season is almost past, suggest that COVID-19 precautions can offer a measure of protection against annual flu as well. A study in Australia found only 33 cases of flu in a study sample of 60,000 people. Chile had a similar result, with just 12 cases in a sample of 20,000 people. These numbers are much lower than average during flu season. Flu cases also dropped dramatically this past spring in the U.S., faster than in prior years.

This encouraging development coincides with widespread use of masks, physical distancing, and frequent handwashing. It’s strong evidence that COVID-19 precautions may very well protect Americans from annual flu as well.

Another bright spot is how quickly the biopharmaceutical industry is developing a COVID-19 vaccine. Although it’s been only nine months since this virus emerged, several drug companies have vaccines in development, with many in advanced study. That’s really fast. I am optimistic that a vaccine may be fielded within the next six to nine months. If it works, it could save tens of thousands, if not millions of lives—and may accelerate lifting pandemic restrictions.

The Unpredictability of COVID-19

Flu and COVID-19 look very similar in their early stages. Other than the loss of taste and smell that occur with COVID-19, it’s virtually impossible early on to tell the difference without testing.

COVID-19 differs from other viruses in its unpredictability and its greater potential for severe consequences. Some cases show no symptoms. Some people will be sick for a week or two with high fever, cough, sore throat, and body aches, but will never need hospitalization. Others have a massive immune response that triggers other issues, including lung problems that can turn deadly. We also see people who seem to have a mild case, start to improve, then suddenly deteriorate and come to the hospital in respiratory distress.

We don’t know exactly why the novel coronavirus affects different people differently, but it’s potentially a combination of factors:

  • The presence of risk factors. The elderly and the obese are at a higher risk of more severe illness, as are those with underlying medical conditions
  • The volume of exposure. Although we don’t know for sure, coming in contact with a small amount of virus may cause less severe illness compared to inhaling a larger quantity
  • Patients’ unique immune responses. For some, the virus puts the immune system into overdrive, spurring more serious repercussions

Although flu rarely leaves lasting consequences, some COVID-19 patients’ symptoms persist for weeks or even months. Lung and heart damage have been reported. We don’t know why some experience these issues while others do not, but a lot of research is underway.

Quarantine guidelines also differ. COVID-19 patients remain infectious for longer than flu patients, so the recommended quarantine is a minimum of 10 days, compared to 5–7 days for annual flu. This quarantine period helps protect others.

Thanks to our decades of experience with annual flu, antiviral drugs like Tamiflu® are readily available by prescription and can be taken at home. But they are not needed by everyone, as healthy individuals tend to recover without treatment.

COVID-19 is a different story. So far, only two drugs have been shown to help, and only in the hospital setting. Remdesivir, an antiviral that slows down the spread of the virus, can help if administered early enough. Dexamethasone is a steroid that can help to quiet the immune system. Neither is a magic bullet and won’t save the sickest patients, but they’re the drug treatments we have currently, and are usually used when patients require admission to the hospital.

When to Seek Help

For both COVID-19 and annual flu, it’s best to isolate yourself to protect others from infection.  Stay in touch with your healthcare provider, continue to take precautions, and remain hydrated—especially if you experience gastrointestinal symptoms.

The most important warning sign—in both COVID-19 and flu—is difficulty breathing. If you find yourself short of breath or cannot do routine things, like walking to the bathroom or up steps, it’s time to reach out to your doctor.

All hospitals have ramped up COVID-19 safety protocols, with temperature checks, masks, patient isolation, and other precautions. MedStar Washington Hospital Center has taken many steps to enhance the safety of patients, so there’s no reason to delay care if you or a member of your family is in serious distress.

A Look Ahead

We are in a very good position, especially compared to a century ago, when the Spanish flu killed millions around the world. But even with advances in technology, ventilators, and modern medicines, we can’t let our guard down. Until a COVID-19 vaccine becomes widely available, it’s absolutely critical to get the annual flu vaccine and continue taking precautions: covering your face, social distancing, and washing your hands or using sanitizer frequently.

If we keep doing the right thing, there’s a very good chance we’ll be out of the woods in a matter of months and the pandemic will subside.

We all want to return to normal. Working together, we can.


Dr. Allen Taylor (Cardiology) and Dr. Aarthi Shenoy (Hematology/Oncology) join Dr. Wortmann to discuss the impact of COVID-19 on the upcoming flu season.

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