Hospitalized COVID-19 patients who also have the flu have a double whammy that brings a much higher risk of severe illness and death than COVID alone, according to a new study.
The findings highlight the need to test COVID-19 patients for the flu and underscore the importance of vaccination against both COVID-19 and influenza, U.K. researchers said.
"We found that the combination of COVID-19 and flu viruses is particularly dangerous. This will be important as many countries decrease the use of social distancing and containment measures," said study co-author Kenneth Baillie, a professor of experimental medicine at the University of Edinburgh.
"We expect that COVID-19 will circulate with flu, increasing the chance of co-infections. That is why we should change our testing strategy for COVID-19 patients in hospital and test for flu much more widely," Baillie said in a university news release.
The researchers analyzed data on nearly 7,000 adults in the United Kingdom who were hospitalized with COVID-19 between Feb. 6, 2020 and Dec. 8, 2021 and tested for other respiratory viral infections.
The 227 patients who had both COVID-19 and the flu were over four times more likely to require breathing support and 2.4 times more likely to die than those with COVID-19 alone, according to the study. The results were published March 25 in The Lancet journal.
"In the last two years we have frequently witnessed patients with COVID-19 become severely ill, at times leading to an ICU admission and the employment of an artificial ventilator to help with breathing," said study co-author Maaike Swets, a Ph.D. student at the University of Edinburgh and Leiden University in the Netherlands.
"That an influenza infection could give rise to a similar situation was already known, but less was understood about the outcomes of a double infection of SARS-CoV-2 and other respiratory viruses," Swets said in the release.
The U.S. Centers for Disease Control and Prevention explains the similarities and differences between COVID-19 and the flu.
SOURCE: University of Edinburgh, news release, March 25, 2022