The flu, a cold or COVID-19? How to tell the difference.

The need to get a flu vaccination is always great, but especially so with the COVID-19 pandemic far from over.
September 1st, 2020
Photo of woman wearing a mask receiving a shot
UCHealth physicians advise patients to get a flu shot early this season and to learn the difference between the flu and the virus that causes COVID-19. Photo: Getty Images.

Knowing the difference between the flu and COVID-19 is essential during the pandemic and it is more important than ever to get a flu shot.

While the approach of fall brings pleasant prospects for many of us: crisp mornings that melt into warm, sunny afternoons; the changing colors of shimmering aspens; the reassuring routine of children returning to school. Each fall, though, brings back an unwelcome visitor: the influenza virus, which for several months starting in September visits various forms of misery on tens of millions with fever, coughing, sore throats, muscle aches and, in significant numbers, hospitalizations and even deaths.

Knowing the difference between flu and the virus that causes COVID-19

Every flu season is challenging for patients and health care providers, but the one approaching is like no other. It will arrive in the midst of the COVID-19 pandemic spawned by the SARS-CoV-2 virus. To say COVID-19 disrupted life in the United States is a considerable understatement. In mid-August, just seven months after seeing its first confirmed case, the country had recorded some 5.7 million cases of the disease and 177,000 deaths caused by it. In Colorado, more than 55,000 people contracted COVID-19 during the same period, and more than 1,900 died from it.

The onslaught of COVID-19 stretched health care resources thin in some parts of the country, but the fight began at the tail end of the 2019-2020 flu season. With the new flu season looming, the strain promises to increase, but people can do their part to ease it by getting a flu vaccination, either with a shot or nasal spray.

The vaccine, though not a foolproof protection against influenza, greatly increases your chances of warding off illness and protecting others from it. That, in turn, will prevent trips to the emergency room and the hospital and reduce stress on health care workers and facilities.

Flu season also brings with it plenty of questions about the disease and the need for vaccinations. Herewith, some answers.

What is the flu?

The flu is a respiratory illness caused by the influenza virus. There are four types of the virus, but only two (A and B) are responsible for the yearly outbreaks we call flu season, which typically stretches from September to March and sometimes April. The disease is highly contagious and spreads primarily through respiratory droplets let loose when a person sneezes or coughs.

Why should I worry about it?

The flu is not the common cold (more on that later). Its symptoms, including fever and body aches, are more intense and last longer. For most people, it causes a week or two of misery before recovery, but last flu season also produced at least 410,000 hospitalizations and at least 24,000 deaths in the United States, according to Centers for Disease Control and Prevention (CDC).

For a detailed analysis of the toll of influenza over the past decade, click here.

How do I protect myself against the flu?

The best move is to get vaccinated. Doing so isn’t a guarantee against infection, but it does lessen the risk considerably to yourself and others. And as Dr. Emily Valenta, who practices family medicine at UCHealth Primary Care – Rockrimmon in Colorado Springs notes, getting the vaccine decreases the chances that you’ll have to go to the hospital or visit the emergency department because of the flu.

“That’s more important this season than ever before,” Valenta said.

Also very important are the basic public health steps most of us have followed for months now in the wake of COVID-19. These include frequent handwashing, maintaining social distancing, wearing masks, and sneezing or coughing into the crook of the arm rather than the hands.

Just what is the vaccine?

The flu vaccine contains pieces of the influenza virus, or antigens. Once administered, our immune systems learn to recognize the enemy and produce armies of antibodies to protect against it. The available shots are trivalent (which protects against two strains of Type A influenza and one of Type B) and quadrivalent (which adds protection against another, rarer strain of Type B). Some, but not all, people ages 2 through 49 can receive a nasal spray vaccine that protects against all four strains of the A and B viruses.

Is one vaccine better than the others?

No. “They are equivalent in terms of protection,” Valenta said. As noted above, the nasal spray vaccine isn’t for everyone.

Who should get vaccinated?

The short answer is, with rare exceptions, everyone six months of age and older. However, it’s particularly important for people 65 years and older, Valenta said. “This is certainly a group that we have identified as high risk and will obviously benefit more from getting vaccinated,” she said.

The CDC also emphasizes the importance of vaccinating children younger than five years old because of their risk of developing serious complications if they are infected by the virus. A list of all groups at highest risk of flu-related complications is available here.

When should I get vaccinated?

It’s always best to do so as early as possible. But this year it is especially important to do so because of the added challenge presented by COVID-19. “The earlier you can protect yourself, the better,” Valenta said.

When will vaccinations be available?

This will vary, but UCHealth plans to make them available at its primary care clinics Sept. 1. Patients with UCHealth will be able to schedule appointments online through My Health Connection, the patient portal. Many other sites will offer the vaccine, including some for free or at reduced cost. The Colorado Department of Public Health and Environment (CDPHE) has more information on available locations throughout the state.

How do I distinguish the symptoms of the flu, the common cold and COVID-19?

The symptoms of the flu and the common cold overlap. Both generally feature runny noses, coughing, headaches and sore throat. However, Valenta said, people who have the flu also often have a temperature of 100.4 Fahrenheit or higher and persistent muscle aches, neither of which is usually a feature of the common cold.

Both flu and COVID-19 can cause symptoms like fever, chest pain, coughing and difficulty breathing, among others. With the end of the 2019-2020 flu season, providers treating patients with these symptoms concentrated on ruling out COVID-19 without worrying much about a flu diagnosis. “But it’s going to be a lot more difficult going into [this] flu season to differentiate between the two,” Valenta said. “We will have to test for both.”

So if this happens will I have to be tested twice?

No. UCHealth can test for several viruses, including those that cause the flu and COVID-19, said Dr. Michelle Barron, medical director for Infection Control and Prevention at UCHealth University of Colorado Hospital on the Anschutz Medical Campus and Professor of Medicine in the Division of infectious Diseases at the University of Colorado School of Medicine. Barron added that UCHealth is waiting to see if the Food and Drug Administration gives emergency use approval to another combination virus test for the flu and COVID-19 viruses. “If they do, we will lobby to have access to the tests and re-agents,” Barron said.

I’ve never gotten the flu and I have no health problems. Why should I get vaccinated?

Valenta said she hears this objection often from patients. I usually respond to this by comparing it to any other preventive measure such as a seatbelt,” she said. “I ask them if they have ever been in a bad car accident and if they say ‘no’ I ask them if they still wear a seatbelt.” That example seems to sway most patients, she said.

Valenta added that she also explains the concept of herd immunity – the idea that increasing the number of vaccinated people reduces the risk of the virus spreading through the community. More people with immunity means fewer opportunities for the virus to find victims – especially the most vulnerable, Valenta said.

I got vaccinated and I got the flu. Why would I do that again?

Simply put, “there is no way to get the flu from the flu shot,” Valenta said. That’s because the trivalent and quadrivalent vaccines contain particles of the influenza virus that have been rendered inactive in the laboratory. The nasal spray contains live viruses that have been “attenuated,” or weakened in the laboratory such that they don’t cause disease.

So what causes the post-vaccination symptoms that people mistake for the flu itself? “What people experience is a brief reaction that typically lasts 24 to 48 hours and involves some low-grade fevers and muscle aches or soreness at the site of injection,” Valenta said. The symptoms are an overresponse by the immune system to the vaccine that “people commonly misinterpret as the actual influenza infection itself,” she added.

I have flu-like symptoms. What should I do?

To the greatest extent possible, stay home, stay hydrated and quarantine. Non-steroidal anti-inflammatory medications can help with muscle aches and soreness. Don’t ask for an antibiotic; drugs that go after bacteria do nothing against a virus, Valenta said. There are prescription antiviral medications, like Tamiflu, that can shorten the duration of illness if you take them soon after symptoms begin, but they are not substitutes for getting the flu vaccine.

If you become acutely ill, especially with a fever, that’s not the time to rush out for your flu vaccine, Valenta cautioned. But she does advise doing so a week or two after you get better. ”It is certainly possible and has happened in the past where patients will get the infection again in the same season, so the flu shot would protect against that potential second infection,” she said.

As we noted earlier, many of the symptoms of the flu and COVID-19 overlap. People who experience symptoms of COVID-19 can schedule a test from UCHealth through some 40 sites around Colorado.

Where can I get more information about the flu?

The CDC is the most comprehensive source. The CDPHE provides regularly updated data for the state of Colorado.


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About the author

Tyler Smith has been a health care writer, with a focus on hospitals, since 1996. He served as a writer and editor for the Marketing and Communications team at University of Colorado Hospital and UCHealth from 2007 to 2017. More recently, he has reported for and contributed stories to the University of Colorado School of Medicine, the Colorado School of Public Health and the Colorado Bioscience Association.