- Influenza infections fell 60% after the introduction of COVID-19 restrictions.
- This reduced exposure to influenza may mean reduced immunity in the population.
- Lifting COVID-19 controls could lead to a major influenza epidemic.
- Anyone who gets the flu shot should take it to reduce the risk.
A study published in the Journal of Infectious Diseases predicted a severe influenza epidemic once COVID-19 controls were lifted, with influenza levels increasing in subsequent years.
Researchers at Columbia University Mailman School of Health used computer modeling to quantify the reduction in influenza transmission and incidence after control measures were implemented. They used this data with data from the Centers for Disease Control and Prevention (CDC)
Non-pharmaceutical interventions (NPI), such as wearing masks, physical distancing, travel restrictions and school closures, have led to a 60% drop in influenza infections within 10 weeks of their introduction. ‘last year. The study suggests that reduced exposure to influenza during control measures will have led to reduced immunity.
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Dr Jonathan Stoye, head of virology at the Francis Crick Institute in London, UK, told Medical News Today: âThis modeling study [â¦] suggests that the reduction in the number of infections in 2020 will lead to a decrease in the immunity of the population and that this could, in turn, contribute to an increase in influenza infections for several years.
Researchers predict that the easing measures could lead to a full-scale influenza epidemic, particularly in parts of the United States where there were high levels of COVID-19 control compliance. They also predict that low flu levels during the pandemic could make it difficult to predict which flu strains in circulation they will need to use to inform future vaccines. This could reduce the effectiveness of flu shots.
On a more optimistic note, the authors concede that the predicted bad flu season is not inevitable. Due to the focus on COVID-19, influenza may have been underreported last year, so more people may have been exposed to the virus than their modeling recognizes.
Alternatively, due to the reduced transmission of influenza, the virus will have been less likely to mutate and produce new variants. So people could be immune to previous influenza infections, resulting in a less severe epidemic.
Professor William Schaffner, professor of preventive medicine at Vanderbilt University School of Medicine, TN, is not convinced by the suggestion of underreporting: âLast year had the lowest incidence of influenza with none. of us can remember because of the restrictions on COVID-19. I don’t think there was an underreporting of the flu. We did not detect a significant drop in testing, but little flu was detected. I think the low flu count was genuine.
But Dr Stoye agrees that the severity of an outbreak depends on the number of variants: “It will be interesting to see if such an increase actually occurs, as the rates of viral infection are determined by multiple factors, such as changes in the rate of appearance of new viral variants.
Professor Schaffner points out that other respiratory infections have increased as life begins to return to normal, suggesting that we need to take the warning of a bad flu season seriously. This summer, with fewer restrictions and the return of children to school, cases of
âThis year, getting the flu shot is more important than ever. While we rightly focus on protecting against COVID-19, we shouldn’t forget about the flu, which can be fatal. “
– Senior Author, Dr Sen Pei, Ph.D, Assistant Professor of Environmental Health Sciences, Mailman School of Public Health, Columbia.
âPredicting the flu is a dangerous job,â says Professor Schaffner. âBecause we had such a weak previous influenza season, has our immunity decreased in such a way that we are susceptible to more transmission and more serious illnesses? The flu is fickle – we’ll just have to wait and see. ”
His advice is unequivocal: âTake the jab. “
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