Viral co-infections in hospitalised COVID-19 patients recruited to the ISARIC WHO CCP-UK study

To assess the prevalence of viral co-infection in a well-characterised cohort of hospitalised COVID-19 patients, and to investigate the impact of co-infection on disease severity.

Multiplex real-time polymerase chain reaction testing for endemic respiratory viruses was performed on upper respiratory tract samples from 1002 COVID-19 patients, aged <1 year to 102 years old, recruited to the International Severe Acute Respiratory and Emerging Infections Consortium WHO Clinical Characterisation Protocol UK study. Comprehensive demographic, clinical, and outcome data were collected prospectively up to 28 days post discharge.

A co-infecting virus was detected in 20 (2.0%) participants. Multivariable analysis revealed no significant risk factors for co-infection, though this may be due to rarity of co-infection. Likewise, ordinal logistic regression analysis did not demonstrate a significant association between co-infection and increased disease severity.

Viral co-infection was rare among hospitalised COVID-19 patients in the UK during the first eighteen months of the pandemic. With unbiased prospective sampling, we found no evidence of an association between viral co-infection and disease severity. Public health interventions disrupted normal seasonal transmission of respiratory viruses; relaxation of these measures mean it will be important to monitor the prevalence and impact of respiratory viral co-infections going forward.