Kids who got flu shot had less severe COVID-19 symptoms, study shows

Abby Haglage
·5 min read

Kids are not yet eligible to receive the COVID-19 vaccine, one of the many complicating factors about reopening schools in the U.S. But while it might be months before they get inoculated, a new review of pediatric data suggests that two other vaccines may protect them from severe illness due to COVID-19 in the meantime.

Researchers at the University of Missouri School of Medicine conducted the study, analyzing the health records of more than 900 kids who tested positive for COVID-19 in 2020. They found that those who received the latest influenza shot were less likely to have respiratory symptoms and less likely to experience severe symptoms from COVID-19 than those who had not received the flu shot. Similarly, those who received the pneumococcal vaccine (which protects against infections like pneumonia and meningitis) were less likely to show severe symptoms of COVID-19.

The news comes after a whirlwind year in which 3 million kids in the U.S. have tested positive for the virus, according to the American Academy of Pediatrics, with more than 117,000 of those cases in the past week alone. Although this age group is more likely overall to experience a mild illness, cases of a strange illness known as multisystem inflammatory disorder in children (MIS-C) are on the rise. The condition is treatable but can be life-threatening.

It also lands during a time in which parents are desperate to have their kids return to in-person learning, as experts estimate that they may have to wait six months or more before the COVID-19 vaccine is authorized for kids.

Dr. Anjali Patwardhan, professor of pediatric rheumatology and child health at MU, as well as the lead author on the study, says her research was motivated by firsthand experience. “In the clinical practice, I saw very commonly that patients who were vaccinated were doing better than the patients who were not,” she tells Yahoo Life. “And then I thought, I should pull the data up and see objectively whether this is true or not.”

Patwardhan was pleased to see that it was, with kids who have been vaccinated against influenza and pneumococcus showing far better outcomes than those who had not. While it’s impossible to know exactly what caused this connection, she says, one explanation could be what’s known as “virus interference.” The phenomenon, first discovered in the 1950s, occurs when a viral infection (or, in this case, a vaccination against it) provides protection from an unrelated virus.

A new study suggests that the flu shot may provide kids some protection against severe COVID-19. (Photo: Getty Images)
A new study suggests that the flu shot may provide kids some protection against severe COVID-19. (Photo: Getty Images)

Dr. Joseph Poterucha, pediatrics chair at the Mayo Clinic Health System in La Crosse, Wis., says experts sometimes worry that something like the flu shot may have an opposite effect by “distracting the body” from SARS-CoV-2 and allowing the virus to quickly multiply in the cells. It was this line of thinking that led to fears of a “twindemic,” a double threat of the coronavirus and the seasonal flu. But with this study, he says, there is evidence that it’s doing the opposite — preparing the immune system using virus-signaling proteins called “interferons.”

“The data is suggesting that the [flu] vaccine ramps up your immune system due to a different mechanism with these interferons ... which prepare the body to fight infection,” says Poterucha, adding, “They interfere, hence the name viral interference.” He says this is unequivocally good news. “It’s very reassuring,” says Poterucha. “There are so many unknowns with COVID and the flu, but it’s really exciting to know that flu vaccine may actually help for COVID.”

Dr. Nina Shapiro, director of Pediatric Ear, Nose and Throat at the UCLA Mattel Children’s Hospital and a professor at the David Geffen School of Medicine, says the mechanism could be even simpler. “There are so many possible reasons for this,” she says. “One could be that if they don’t have other illnesses such as a pneumococcal illness or influenza, they have less of an inflammatory or inflamed respiratory tract, which may make them less susceptible to severe COVID-19.”

Another, she says, could be differences in the demographics of the vaccinated group and the unvaccinated group and the health disparities that may result. Indeed, vaccination rates are often lower in communities of color, which have been hit hardest by the pandemic. This is one of the things Patwardhan wanted to explore. “The lowest rate of flu vaccination is in Black populations, followed by Hispanic populations,” the study author says. “And if you also look at the COVID severity percentage, Black individuals are doing the worst followed by Hispanic individuals.”

“Based on these findings, we hypothesize that the higher incidence of COVID-19 in minority populations may also reflect their low vaccination rate apart from other health inequalities,” Patwardhan added in an MU press release.

Although more research is needed, all three experts seem to agree that this data underscores the importance of getting kids vaccinated. “It’s one more reason to get the influenza vaccine,” says Shapiro. “Obviously the main reason is to prevent influenza, but if it also helps mitigate COVID-19 infections then that is a secondary benefit.”

“One hundred percent get your children vaccinated for influenza,” adds Poterucha. “The data is showing that it will benefit them in terms of their symptoms and also in terms of their abilities to transmit to other people — including you and your loved ones who may be at risk with medical comorbidities.”

Patwardhan hopes that other places will begin to evaluate data on kids with COVID-19 to bolster this research. But in the meantime, she wants the current findings to underscore the benefits of getting the flu shot. “Taking flu shots helps not only from the flu, but also can help you with the other ongoing pandemic infections,” she says. “If we can reduce the severity of the disease by viral interference in children, that’s very useful.”

For the latest coronavirus news and updates, follow along at According to experts, people over 60 and those who are immunocompromised continue to be the most at risk. If you have questions, please reference the CDC’s and WHO’s resource guides.

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