Fully three quarters of COVID-19 patients receive antibiotics, although fewer than 10% have a bacterial infection, according to a new research review.

An analysis of 154 studies involving more than 35,000 patients revealed that the prescribing level was significantly higher than the estimated prevalence of bacterial co-infection, reported Derek R. MacFadden, M.D., of the Ottawa Hospital Research Institute in Ontario. Patient data was stratified by geographical region, severity of illness and age.

Antibiotic prescribing rose as patient age increased and was also high in patients requiring mechanical ventilation, MacFadden added. Yet in 31 studies, estimated bacterial coinfection was 8.6%.

“Unnecessary antibiotic use is likely high in patients with COVID-19,” the researchers concluded.

The study was published in the journal Clinical Microbiology and Infection.