Coronavirus death risk triples for patients also battling another airway infection, study suggests

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Sick woman with flu, cold, fever and cough sitting on couch at home. Ill person blowing nose and sneezing with tissue and handkerchief. Woolen socks and medicine. Infection in winter. Resting on sofa.
The coronavirus has dominated headlines for more than a year, however, other respiratory infections continue to circulate. (Posed by a model, Getty Images)

Enduring the coronavirus alongside another viral, bacterial or fungal infection in the airways more than triples a patient's risk of death, research suggests.

The UK's various lockdowns have helped to stem a range of infections. Heightened awareness around the effectiveness of vaccines also prompted a record number of people to take up the flu jab.

Nevertheless, the coronavirus is far from the only infection humans are exposed to amid the pandemic.

Scientists from the University of Wisconsin School of Medicine and Public Health have now revealed people with a "co-infection" – enduring the coronavirus and another respiratory pathogen simultaneously – are over three times more likely to die.

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So-called super-infections – "the subsequent recovery of other respiratory pathogens during care for [the coronavirus] infection" – pose a similar risk, the results suggest.

This comes after the BMJ reported people who endure both flu and the coronavirus are more than twice as likely to die as those who just have the latter infection.

Viruses in human lungs, 3D illustration. Conceptual image for viral pneumonia, flu, MERS-CoV, SARS, Adenoviruses and other respiratory viruses
Catching the coronavirus alongside another respiratory infection raises a patient's death risk, research suggests. (Stock, Getty Images)

Like many respiratory infections, the coronavirus primarily spreads face-to-face when infected droplets are expelled in a cough or sneeze.

Past research suggests around a quarter (25%) of older people who catch seasonal flu also endure a secondary bacterial infection.

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Co-infections and super-infections have been reported in coronavirus patients, however, data on their prevalence was "scarce".

To learn more, the Wisconsin scientists analysed 118 studies carried out between 1 October 2019 and 8 February 2021. The coronavirus was formally identified on 31 December 2019.

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Results – published in the journal PLOS One – suggest nearly one in five (19%) people who have the coronavirus also endure a secondary infection in their airways. Of these co-infections, 10% are viruses, 8% bacteria and 4% fungi.

Super-infections are estimated to affect just under a quarter (24%) of coronavirus patients, of which 4% are another virus, 20% bacteria and 8% fungi.

Enduring either a co-infection or super-infection was found to more than triple a patient's death risk.

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Super-infections were linked to a 45% higher risk of a patient requiring ventilation, compared to a co-infection.

Co-infections were associated with a longer hospital stay, however – 29 days on average compared to 16 days among those with a super-infection.

"The presence of either co-infection or super-infection was associated with poor outcomes, including increased mortality," concluded the scientists. 

"Our findings support the need for diagnostic testing to identify and treat co-occurring respiratory infections among patients with [the coronavirus] infection."

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