An increase in the number of non-COVID-19 respiratory infections should be expected this winter, say scientists. The warning comes following the results of a new study, published in The Lancet Regional Health – Europe, which found that over 55% of respiratory disease hospitalizations during the pandemic's peak were caused by non-SARS-CoV-2 infections.

The University Bristol-led study funded and conducted in collaboration with Pfizer Inc., as part of AvonCAP, is the first to compare the number of hospitalizations from respiratory disease infections caused by COVID-19 and non-SARS-CoV-2 infections.

Using data from 135,014 hospitalizations from two large hospitals in Bristol between August 2020 and November 2021, researchers identified 12,557 admissions attributable to acute Lower Respiratory Tract Disease (aLRTD) with patients admitted with signs or symptoms of respiratory infections including cough, fever, pleurisy, or a clinical or radiological aLRTD diagnosis. Of these, 12,248 (98%) patients, comprising mainly older adults, consented to participate in the study.

Following further analysis, the team show that of the 12,248 aLRTD hospitalizations, 55% (6,909) were due to infection with no evidence of SARS-CoV-2, while confirmed SARS-CoV-2 infection only accounted for 26% (3,178) of respiratory infections. The remaining 17% (2,161) were due to infection with no infective cause.

Adam Finn, Professor of Pediatrics at the University of Bristol, Director of the Bristol Vaccine Centre at Bristol Medical School and lead ofBristol UNCOVER(Bristol COVID Emergency Research Group),said: "What is really surprising from our results is just how much other non-COVID respiratory infections there was during this time, other infections clearly didn't just disappear and despite significant public health measures, including both vaccination and non-pharmaceutical intervention such as masks, our findings show there was still a high incidence of non-COVID-19 disease causing hospitalizations alongside COVID-19 patients."

Our results really highlight not only the huge burden of respiratory infection on the NHS and other healthcare systems, but also how bad things may get this winter. It is therefore essential that appropriate healthcare planning and resource allocation is undertaken to care for patients with respiratory conditions, in addition to implementation of public health measures to reduce respiratory disease burden and improve patient outcomes."

Dr Catherine Hyams, Study Lead Author, Post-Doctoral Clinical Research Fellow and Principal Investigator, University of Bristol

The study is part of AvonCAP, an ongoing collaborative surveillance project funded by Pfizer Inc., which records detailed information on every adult patient admitted to Bristol's two large NHS hospitals with symptoms, signs and/or X-ray evidence of acute disease in the lungs.