A vaccination record card and face mask on a table.

September 15, 2021

The flu may have been less threatening last year, but that’s thanks to many of us staying at home much of the fall and winter of 2020.

We shouldn’t expect the same this year.

The flu virus—itself capable of making the young and elderly severely ill—is expected to return with its usual force, as people increasingly venture out and travel more.

“Getting the flu vaccine is an important step in preventing illness in you, your family and the community, as we continue to battle the pandemic,” says Dr. Annamaria Macaluso Davidson, MD, vice president of Employee Health Medical Operations for Memorial Hermann Health System.

So how do we protect ourselves against two contagious viruses at the same time? She offers her prescription, while answering common questions as we enter flu season this month.

Q: Do you need to space out the flu vaccine and COVID-19 vaccines or booster shots?

A: They can be given at the same time. “Our bodies can handle receiving both at the same time and produce sufficient immune response to both viruses,” she says.

They even can be given in the same upper arm—and you won’t have any worse side effects. These may be nonexistent or mild: redness and soreness at the site, low-grade fever, chills, aches or fatigue for a day or two.

“Consider them signs that your body’s immunity is responding well,” Dr. Macaluso Davidson says. “Acetaminophen or ibuprofen should make you feel better.”

Q: Is flu down because of COVID-19?

A: Yes, though it’s not due to the virus itself. Rather, our actions to avoid the coronavirus also have kept the flu at bay.

Social distancing, masks and frequent handwashing have helped fight both viruses, as have traveling less and staying home more, including when ill.

But, as people become ready for normalcy and weary of protective measures, “we expect more flu cases,” she says. “More students are attending classes in person, and people are out and about more in the community.”

Q: Given that the flu was down, were scientists still able to create an effective vaccine?

A: Yes. Vaccines are created based on previous strains, and researchers had the data they needed to build a vaccine that will greatly slash symptoms.

“If you get vaccinated, even if you get flu later on, you’ll have a much milder course and you’ll get better faster,” Dr. Macaluso Davidson says.

Q: What are the differences between flu and COVID-19?

A: Both are respiratory illnesses spread in the air or through droplets on surfaces due to coughs and sneezes. They also share such symptoms as fever, achiness, fatigue and nasal congestion. COVID-19 also can cause vomiting, diarrhea or loss of taste and smell.

Flu is less contagious than COVID-19, especially the fast-spreading delta variant.

Flu and COVID-19 infect people of any age, with more severe illness in the unvaccinated and those with certain health conditions. With COVID-19, or SARS-CoV-2, adults generally become sicker than children. The same is not necessarily as true with flu.

Signs of flu often arise 1 to 4 days after exposure, while COVID-19 symptoms tend to occur 5 to 6 days after exposure, with 97% showing symptoms by day 11 and the remaining by day 14.

Most unvaccinated people with flu will be sick for about a week, but are unlikely to be hospitalized. Unvaccinated people who catch COVID-19 are more likely to have severe symptoms or be hospitalized.

The flu vaccine is a one-and-done, as is the Johnson & Johnson COVID-19 vaccine. The Pfizer-BioNTech and Moderna vaccines for the coronavirus require two shots, with a possible booster later.

The flu vaccine is offered for those ages 6 months and up, whereas COVID-19 vaccines are for those ages 12 and up. Both are safe during pregnancy and breastfeeding.

Q: Can you get the flu and COVID-19 at the same time?

A: You could, but it’s highly unlikely.

“Sometimes when you’re fighting an infection your immunity is lower and you’re more vulnerable if you’re exposed to something else that is contagious. But that has been much rarer with flu and COVID-19,” she says.

It is similar to the infrequency of children being hospitalized for SARS-CoV-2 and another respiratory disease, RSV, or Respiratory Syncytial Virus.

Q: Who's most at risk if they catch the flu?

A: Since flu vaccines are offered to those 6 months old and up, infants younger than 6 months cannot be inoculated, so they’re most vulnerable. That’s why their parents, caregivers, siblings and others they come in contact with need to be vaccinated. “It’s important to create a protective bubble around babies,” she says.

Those with lower reserves to fight infections, including the flu, are people over 65 and those with diabetes, cancer, HIV, kidney disease or auto-immune diseases. Children, pregnant women and asthmatics also are more vulnerable to more serious repercussions.

Q: When should we vaccinate for the flu?

A: Flu is seasonal. It’s generally an illness in the fall and winter, from October into March—and sometimes April—when we are more likely to be indoors. That’s why flu inoculations tend to be offered from late September through December.

“Unlike flu, COVID-19 is not associated with seasons,” Dr. Macaluso Davidson says. “It comes in surges and waves.”

To learn more about flu vaccines, visit a Memorial Hermann primary care physician.

The information in this article is accurate as of September 15, 2021.

In Dec. 2021, the CDC issued a preferential recommendation for the use of the mRNA COVID-19 vaccines currently available in the U.S. (Pfizer and Moderna) over the Johnson & Johnson vaccine, citing rare but serious side effects. Throughout the pandemic, Memorial Hermann has closely followed guidance from the CDC as well as the U.S. Food & Drug Administration (FDA) and the State. As such, Memorial Hermann now recommends the Pfizer and Moderna COVID-19 vaccines over the Johnson & Johnson vaccine for those who meet vaccine eligibility.

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