By Kathleen Berger, Executive Producer for Science & Technology
Children who receive a flu shot are less likely to suffer symptoms from a COVID-19 infection, according to a new study from the University of Missouri School of Medicine. The study showed that a flu shot may help protect children against the effects of COVID-19.
“Generally I saw in the clinics and in the hospital that the patients who were vaccinated did better generally. So, I decided to collect data on them,” said Anjali Patwardhan, MD, MU Health Care Pediatric Rheumatologist.
Patwardhan reviewed the charts of more than 900 patients, ages 20-years old and younger, who were diagnosed with COVID-19. She found that the patients who had received a flu vaccine in the current flu season had lower odds of experiencing COVID-19 symptoms, including respiratory problems and severe disease.
“The odds of having a severe disease or odds of having a symptomatic disease was less in children who had a flu vaccination,” she said.
Patwardhan said this may be due to a phenomenon called viral interference, in which the growth of a new virus can be inhibited by a previous viral infection. This can occur even when the first virus invader is an inactivated virus, like the flu vaccine. While more research is needed to see if other factors are at play, the data suggest the flu vaccine offers a possible advantage.
For 2021, flu vaccines may help protect children as COVID-19 vaccines may not be approved for all children until early next year. Flu activity peaks between December and February, but activity can last as late as May.
Other types of vaccines may also give what the investigators of a different study call “trained immunity”. Last September, before the COVID-19 vaccines were available, some St. Louis health care workers chose to participate in an international clinical trial on the Washington University Medical Campus. Investigators wanted to see if frontline health care workers receiving the vaccine for measles, mumps and rubella- the MMR vaccine- could have a strengthened immune response to viral infections that would protect them from COVID-19. If participants acquired trained immunity, researchers wanted to know how long it would last.
But once the new COVID-19 vaccines rolled out, recruitment in countries distributing COVID-19 vaccines, including the U.S., had stopped.
Michael S. Avidan, MBBCh, the Dr. Seymour and Rose T. Brown Professor and head of the Department of Anesthesiology at Washington University is principal investigator, leading the COVID-19 Research Outcomes Worldwide Network Collaborative, or CROWN. Co-investigator Mary Politi, PhD, is a leader in health decision-making and a professor of surgery in the Division of Public Health Sciences at Washington University. Avidan and Politi are evaluating whether the MMR vaccine can truly protect against COVID-19 by decreasing the number of infections and severity of infections.
The research team launched a sub-study, looking at markers of trained immunity with participants who received the MMR vaccine. It’s believed the MMR vaccine could broadly boost an individual’s immunity and prevent infection from SARS-CoV-2 for a limited period. This is because the vaccine carries small amounts of the live, weakened viruses that could train the body’s immune system to fight multiple pathogens.
“If I say to you now, I’m going to run around Forest Park. If I’ve been training to run around Forest Park for a few weeks before, I would do much better running around Forest Park now. We similarly discovered that the immune system of the body actually does well when it’s trained to respond to infections. Where we’ve discovered this in particular is in relation to weakened organisms that are used as vaccine,” said Avidan.
“The immunity to the specific viruses of measles, mumps and rubella lasts a long time, hopefully a lifetime,” said Politi. “But (boosted immunity from MMR vaccine) to other viruses and other pathogens that you may be exposed to, that immune response is probably months to years. We don’t know exactly how long.”
The researchers also want to know if the MMR vaccine primes the immune system to be more responsive to other viruses and other vaccines, including the COVID-19 vaccines.