We investigated the frequency and microbiological details of bacterial co-infection and secondary infection, in addition to antimicrobial usage in 48,902 patients hsopitalised with COVID-19 during the first pandemic wave. We found that Covid-19 related respiratory or bloodstream bacterial infection was rare (n=1,107); the majority (71%) were secondary infection, acquired >48 hours after admission. However, antimicrobial use is high with 37% prescribed pre-hospital antimicrobials, while 85% received one or more antimicrobials during their hospital stay.

Based on our data, we recommend a range of existing antimicrobial stewardship interventions that should be prioritised for incorporation into COVID-19 patient care to mitigate worsening of antimicrobial resistance. As well as restricting prescribing without a confirmed diagnosis, these include tailoring the choice of antimicrobials (when required) to likely pathogens and local resistance patterns, and encouraging clinicians to discontinue antimicrobials if co-infection is deemed unlikely and tests confirm that patients do not have a bacterial infection.