Sometimes the tool you need is right there in the toolbox.
None of the COVID-19 vaccines has been approved for children yet, but researchers around the world are studying the potential of existing childhood immunizations. And one U.S. team has found the flu shot could provide protection against the novel coronavirus.
University of Missouri researchers reviewed the records of more than 900 children who tested positive for COVID-19. They found those who had received the influenza vaccine in the current flu season were less likely to have severe COVID-19 illness, respiratory problems, or any symptoms at all.
“The patients who actually were vaccinated (with) flu vaccine actually did better in the clinical scenarios. They were not as sick,” lead author Dr. Anjali Patwardhan told Global News.
The professor of pediatric rheumatology says it’s possible the flu shot causes “viral interference.”
“(Flu shots) can actually give a temporary immunity for the subsequent viral infection,” said Patwardhan.
“It is known that the growth of one virus can be inhibited by a previous viral infection.”
Patwardhan says more studies are needed, but she suspects the shot’s inactivated or weakened influenza virus could interfere with the reproduction of the novel coronavirus.
Calgary pediatric infectious diseases specialist Jim Kellner says the concept has been studied with other viruses.
“This is actually a ‘thing’ in infectious diseases that we’ve known about for a long time,” said Kellner.
Rhinovirus, the predominant cause of the common cold, has been shown to compete with influenza A.
“It is competition in general for the nutrients and the reaction or responses of the cells in a way that we don’t understand completely,” said Kellner.
He points out there are a number of existing vaccines with potential to protect against COVID-19 and researchers are exploring the possibilities.
“There are dozens of studies looking at BCG (tuberculosis vaccine) to prevent COVID. There are a handful of studies looking at MMR (measles, mumps, rubella vaccine) to prevent COVID, and even one study looking at polio.”
Kellner explains vaccination stimulates the immune system to produce antibodies to fight the target disease. But it can also have non-specific effects, known as “immune training.”
“Your innate immune system has been trained to do a better job of fighting (a virus) off in the first place, even if it’s the first time that it’s seen it.”
In parts of the world with high childhood mortality, both the BCG and MMR shots have been shown to reduce deaths overall, suggesting their protection goes beyond the diseases they target.
That could also explain why COVID-19 tends to hit adults much harder than children. Routine immunizations happen early in life, and immune training can wane over time.
Patwardhan’s team also found evidence of the pneumococcal vaccine lowering the odds of symptomatic COVID-19.
She suspects the higher incidence of COVID-19 among minority populations could reflect their historically low routine vaccination rates.
Patwardhan says the research is a good reminder to update your immunizations and get a flu shot.
“If you’re not vaccinated, please go and get vaccinated.”