What Will Happen When Flu Season Meets the COVID-19 Pandemic?

In a nutshell…
As the Northern Hemisphere flu season approaches amidst the COVID-19 pandemic, many of the same infection control measures used during the pandemic could help reduce flu cases. This article compares the two viral illnesses and the actions people can take to help prevent them.


What will happen when the 2020 flu season meets the COVID-19 pandemic? Will we be in a new “world of hurt” as the vulnerable succumb to one or both infectious diseases? Or, will we be more protected than ever from flu, thanks to infection control measures already in place for COVID-19? Much depends on us. According to a Web MD interview with Dr. Robert Redfield, Director of the U.S. Centers for Disease Control and Prevention (CDC), the same guidelines issued to prevent the spread of COVID-19, such as social distancing, wearing face masks, and washing hands frequently, also could help reduce flu transmission…if we stay vigilant.

Flu vs. COVID-19 

According to CDC, flu and COVID-19 are similar respiratory illnesses with several significant differences. Both are caused by viruses, but less is known about the COVID-19 virus (a type of coronavirus) than flu (or influenza) viruses. The table below identifies similarities and differences between these two diseases. Nevertheless, people who develop respiratory symptoms in the coming months may require testing to know which illness they have.

Flu and COVID-19 Similarities Significant Differences
Symptoms Fever or feeling feverish/chills, cough, shortness of breath or difficulty breathing, fatigue (tiredness), sore throat, runny or stuffy nose, muscle pain or body aches, headache, and vomiting and diarrhea COVID-19 may include a change in or loss of taste or smell
Time from infection to symptoms At least 1 day It may take a person longer to develop COVID-19 symptoms (2-14 days) than flu symptoms (1-4 days)
Period of being contagious At least 1 day Most people can spread flu for about 1 day before showing symptoms. The spread of COVID-19 is still being studied, but it is possible for someone to spread the disease for about 2 days before showing symptoms and remain contagious for at least 10 days
How they spread Person-to-person, mainly by airborne particles when they land in the mouths or noses of people nearby (or perhaps inhaled into the lungs); also, possibly by touching a surface contaminated with the virus and then touching one’s mouth, nose, or possibly their eyes COVID-19 appears to be more contagious among some populations and age groups than flu; COVID-19 appears to have more super-spreading events, which, according to CDC, means the virus that causes COVID-19 can quickly and easily spread to many people and result in continuous spreading as time progresses
People at higher risk Older adults (65 and older); people with underlying medical conditions; pregnant women Flu is associated with a higher risk of complications in healthy children; school-aged children infected with COVID-19 are at higher risk of a rare but severe complication
Complications These can include pneumonia, respiratory failure or distress, sepsis, cardiac injury, multiple organ failure, worsening chronic medical conditions, inflammation of the heart, brain, or muscle tissues, or secondary bacterial infections Additional complications from COVID-19 can be blood clots in the veins and arteries of the lungs, heart, legs, or brain and Multisystem Inflammatory Syndrome in children
Treatment Those at high risk of complications or those who have been hospitalized should receive supportive medical care to help relieve symptoms/complications Flu treatment includes FDA-approved antiviral drugs; the National Institutes of Health has guidance on treatment of COVID-19; Remdesivir is being explored as a treatment for COVID-19 and is available under an Emergency Use Authorization

Clues from the Southern Hemisphere

Each year, the severity of the Southern Hemisphere flu season can be an indicator of what’s to come in the Northern Hemisphere. The World Health Organization’s (WHO’s) most recent Influenza update notes, “The various hygiene and physical distancing measures implemented by Member States to reduce SARS-CoV-2 [coronavirus] virus transmission have likely played a role in reducing influenza virus transmission.” That said, the WHO warns flu surveillance data should be “interpreted with caution” as the COVID-19 pandemic has influenced “health seeking behaviors, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States.” So, while recognizing potential reporting difficulties may be contributing to a rosier picture than reality warrants, the relatively mild flu season in the Southern Hemisphere could be a good indication for the north.

Vaccines: The State of Play

Despite tremendous progress to develop safe and effective COVID-19 vaccines, we have not yet reached that goal. Flu vaccines, however, are readily available, and the CDC has purchased millions of extra doses to distribute this fall to reduce the number of cases. Dr. Redfield issued a plea to all of us: “Please don’t leave this important accomplishment of American medicine on the shelf. This is a year that I’m asking people to really think deep down about getting the flu vaccine.” The CDC Director would like to see 65% of the U.S. population vaccinated against the flu this year. Last year’s vaccination rate was about 45%. Adults 65 years of age and older should consider getting the high dose or “adjuvanted” vaccine for a better immune response. Older adults need to remember to get the flu shot and not the nasal spray vaccine.

But there are obstacles to accessing vaccinations of all types as we observe social distancing. The National Foundation for Infectious Diseases (NFID) notes, “Unfortunately, it’s impossible to get vaccinated from the comfort of your own couch. As a result, we have seen a troubling drop in routine immunization rates across all age groups in the U.S. We must reverse this trend now; otherwise, we could see outbreaks of dreaded vaccine-preventable diseases across the country, which would be a disaster, particularly during a pandemic.” Flu vaccines are generally widely available in the U.S., including at pharmacies in drug stores and supermarkets. Wherever you go to get your flu shot, remember to maintain a social distance of at least six feet from others as you wait in line, wear a face mask and do not touch it, and use hand sanitizer frequently (at least 60% alcohol) while you are out and about. NFID identifies strategies to make vaccinations quick, easy, and safer—including setting up vaccine “clinics” in parking lots and scheduling separate office hours for vaccinations.

Be Proactive for Your Health

This flu season, redouble your efforts to maintain a healthy lifestyle that includes a balanced diet, regular exercise, and adequate rest. Make sure you and your family members are vaccinated against flu, continue to wear a face mask and social distance in public, and wash your hands thoroughly and frequently. Disinfect frequently touched surfaces with surface disinfectants approved for use against COVID-19, or use regular household bleach according to CDC directions. (We used those directions to develop a bleach disinfection poster, and by following those directions you can destroy both the COVID-19 and flu viruses on surfaces.) 

With vigilance, we can get through the “1-2-punch” of flu season and pandemic in good health.


Ralph Morris, MD, MPH, is a Physician and Preventive Medicine and Public Health official living in Bemidji, MN.

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