The measures taken during the Covid-19 pandemic have not only changed the spread of the coronavirus, but also the way influenza and other respiratory viruses circulate. A new study published in the scientific journal PLOS Global Public Health shows that the pandemic restrictions have shifted the seasonal peaks of these infections earlier, even affecting the trend of deaths from cardiovascular diseases.
The study, led by scientists Michael Sieber and Arne Traulsen of the Max Planck Institute for Evolutionary Biology, analyzed 14 years of epidemiological data in Germany.
Before the pandemic, influenza and respiratory syncytial virus (RSV) typically peaked in February and March. After the COVID-19 lockdown, seasonal epidemics returned much earlier, often in December or earlier.
According to researchers, the main reason is related to the decrease in collective immunity. Physical distancing, the use of masks and the reduction of social contacts prevented the normal circulation of respiratory viruses. As a result, more people were left without developing natural immunity and became susceptible to infections in subsequent seasons.
When restrictions were lifted, viruses found a larger number of vulnerable people, spreading faster and bringing epidemic peaks earlier than usual.
The study also found that this shift was also reflected in seasonal increases in deaths, particularly those related to cardiovascular disease. According to the authors, respiratory infections are a significant risk factor for heart attack, stroke and other heart complications.
Scientists emphasize that monitoring population immunity and increasing vaccine coverage are essential to more accurately predict future flu seasons and better organize preventive measures.
According to them, the history of a population's exposure to viruses may be as important as the characteristics of the virus itself in determining when seasonal epidemics break out.
