Skip to main content
Jefferson Health

Home of Sidney Kimmel Medical College

COVID-19 and the Flu: Will there
be a ‘Twindemic?’

It is possible to get both COVID-19 and the flu at the same time. Here’s how to protect yourself when two similar viruses collide.

Listen to an episode of The Health Nexus Podcast that compares and contrasts symptoms of allergies, the common cold, and the flu with the coronavirus.

The COVID-19 pandemic is about to come face-to-face with an annual public health foe: influenza. The situation is serious enough that Robert Redfield, director for the Centers for Disease Control and Prevention (CDC), warned in an early August interview that the U.S. could have the “worst fall, from a public health perspective, we’ve ever had.”

It’s unknown whether fall will bring a predicted “second wave” of COVID-19 cases. “But what is known is that the combination of COVID-19 and flu season will be confusing for many people,” says Dr. John Zurlo, Chief of Infectious Diseases at Thomas Jefferson University Hospital. It’s even possible for people to get both COVID-19 and the flu at the same time. Several such cases were seen early on in the pandemic.

Influenza, COVID-19 and other respiratory viruses can carry nearly identical symptoms, including fever, cough, shortness of breath, fatigue, sore throat, nasal congestion and aches and pains. As a result, it will be difficult for people to tell which virus they might have (or if they have both) without getting tested. “Loss of taste or smell is one symptom that appears to be specific to COVID-19, but even so, we’re not sure how common that symptom truly is,” Dr. Zurlo says.

Make no mistake, influenza has serious health impacts. According to the CDC, last year’s flu season affected as many as 56 million Americans, led to as many as 740,000 hospitalizations and caused up to 62,000 deaths.

The overlap of flu and COVID-19 makes it important for everyone—especially people who live in multigenerational households—to take extra caution this fall. Jefferson experts recommend these five tips:

1. Get a flu shot — early. According to the CDC, the flu vaccine has been shown to reduce the risk of having to go to the doctor with flu by 40% to 60%. While the vaccine won’t prevent COVID-19, “It will place the flu lower on the list of possible viral illnesses you may contract this year, which is why I encourage everyone to get vaccinated,” Dr. Zurlo says. The CDC typically recommends getting vaccinated in September or October to provide maximum protection throughout the length of the flu season. The influenza vaccine is quadrivalent, which means it offers protection from four strains. (The CDC website lists the specific strains covered in the 2020-21 vaccine.) “It typically takes two weeks for the flu shot to become fully effective after vaccination,” says Dr. Ellen O’Connor, medical director for the Jefferson Occupational Health Network. The flu vaccine is recommended for anyone 6 months of age or older, while people ages 65 and older should get a high-dose flu shot. Don’t fall for flu vaccine myths. “The flu shot does not cause people to get the flu,” Dr. O’Connor says.

2. Remain vigilant. The precautions many people have taken during the COVID-19 pandemic will also protect people from influenza, colds and other respiratory viruses. Wear masks—especially indoors—when around other people. Make sure your mask covers your nose and mouth. Continue following social distancing and hand hygiene guidelines. Avoid large crowds and public spaces.

3. Watch for symptoms. Take them seriously. If you don’t feel well, stay at home. If your children don’t feel well, keep them away from school or other activities. Seek care as soon as you experience symptoms. Dr. Zurlo recommends using telehealth options to connect with primary care providers; they can do an assessment during a video call and direct you to a testing site if needed. “We will conduct widespread testing for both COVID-19 and influenza,” Dr. Zurlo says. Jefferson Health is expecting to have the ability to test for both viruses with the same swab.

4. Practice extra caution in multigenerational households. More recent data locally and nationally suggest a rise in the number of children, adolescents and young adults testing positive for COVID-19. “In July in the City of Philadelphia, about 60% of new COVID-19 diagnoses were in people less than 40 years old,” Dr. Zurlo says. Some of them are asymptomatic, meaning they could be spreading COVID-19 without knowing it. Just as concerning, some of the older people in Philadelphia more recently diagnosed with COVID-19 live not in nursing homes, but in multigenerational homes. “You could make an argument that children and young adults should wear masks around older vulnerable people, even indoors,” says Dr. Zurlo.  Another option: keep children and adults in separate rooms if they show symptoms of any respiratory illness.

5. Keep an eye on influenza activity. Throughout each flu season, the CDC publishes weekly surveillance reports on its flu website. “Be on the lookout to see if flu activity is more sporadic or widespread,” Dr. Zurlo says. Many state and local agencies, including the Philadelphia Department of Health, Pennsylvania Department of Health and New Jersey Department of Public Health, monitor flu activity locally.

Reasons for Optimism

While everyone should prepare for the worst, Dr. Zurlo and other public health professionals see some potentially optimistic signs heading into this fall.

For one, the number of new cases statewide in Pennsylvania has remained steady since peaking in May. “Right now we’re in a very good place in comparison to most states,” Dr. Zurlo says.

In addition, health systems like Jefferson have cared for thousands of COVID-19 patients and are well-positioned to handle any potential surges that involve both COVID-19 and influenza.

When it comes to influenza, one indicator of the level of seasonal flu activity comes in cases seen in other parts of the world prior to the U.S. flu season. In August 2020, the World Health Organization reported that global influenza activity was at “lower levels than expected for this time in the year,” with the caveat that the influenza season has not yet started in the temperate zones of the southern hemisphere.

But staying safe this fall isn’t a matter of optimism or pessimism. It’s a matter of taking all health risks seriously. “By wearing masks, washing hands, avoiding enclosed public places and social distancing, people will help reduce the spread of respiratory infections in general and will keep the number of COVID-19 cases down until we get a vaccine, of which I remain optimistic,” Dr. Zurlo says.

, , ,
COVID-19, Healthy You