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In the study published in Science, the researchers combined data on the spread of seasonal flu, its genetic makeup, and international travel patterns to study how the viruses moved and evolved. This approach helped to estimate how long the viruses remained in certain regions during periods of high and low volumes of international travel and how their genetic diversity changed before, during, and after the COVID-19 pandemic.
Seasonal flu epidemics place a heavy strain on healthcare systems, leading to over 5 million adult hospitalisations annually. Developing effective vaccines relies on tracking flu strains as they spread globally. Reduced human movement during COVID-19 offered a rare chance to study how seasonal flu is affected during a pandemic.
During the COVID-19 pandemic seasonal flu levels dropped worldwide due to restrictions on movement and mixing. However, once air travel returned there was a rapid bounce back, showing that the virus was in most cases maintained during the pandemic with continued viral movements and accumulation of genetic diversity.
Lead author of the study, Zhiyuan Chen said, ‘It was remarkable how quickly seasonal flu re-established to a pre-pandemic equilibrium just a few years after the height of the COVID-19 pandemic.'
Read the full story and the paper on the Oxford Martin School website.