Increase in circulation of non-SARS-CoV-2 respiratory viruses following easing of social distancing is associated with increasing hospital attendance.

Dear editor,

In this Journal, we recently reported that the appearance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and the accompanying social restrictions were associated with a dramatic reduction in circulation of non-SARS-CoV-2 viruses. We have also previously reported on the resurgence of rhinovirus circulation following the re-opening of schools in the United Kingdom in September 2020. Apprehension now surrounds the effects of complete cessation of social distancing measures in the United Kingdom on the transmission of SARS-CoV-2, and other respiratory viruses. The effect of social distancing on suppressing respiratory viruses are well documented, therefore, as these restrictions ease multiple routes of transmission increase.

At University Hospital Southampton NHS Foundation Trust (UHSFT), UK, we have tested all adult medical patients admitted to hospital using point-of-care multiplex PCR testing (using the QIAstat-Dx Respiratory SARS-CoV-2 panel and the BioFire Respiratory Panel 2.1 plus) for a wide range of respiratory viruses, since the start of the SARS-CoV-2 pandemic. From 20th March 2020 to the 30th June 2021, 17,804 adult patients were tested. There was a near absence of detection of non-SARS-CoV-2 respiratory viruses following the introduction of social distancing measuring during the first wave of the pandemic. In addition to the increases seen in rhinovirus detection after September 2020, detections of parainfluenza viruses and non-SARS-CoV-2 coronaviruses were seen to increase after the 18th April 2021. This corresponds with the opening of non-essential retail and outdoor hospitality in England on the 12th April 2021. There was a further sharp increase following the resumption of indoor socialising and hospitality which started on the 17th May 2021 (Fig. 1 ). At peak circulation, 13% of admitted adult patients had parainfluenza viruses detected and 5% had non-SARS-CoV-2 coronaviruses detected. These findings are consistent with national surveillance data. Furthermore, Emergency Department attendances for acute respiratory illness increased at UHSFT following schools returning after the Easter holidays on the 8th March 2021. This corresponded with an increase in rhinovirus detection. Thereafter, a further sustained increase in Emergency Department attendances has been seen coinciding with increased parainfluenza and non-SARS-CoV-2 detection (Fig. 2 ).

Fig. 1

Proportion of tests positive for non-SARS-CoV-2 respiratory viruses over time.

Fig. 2

Emergency department attendances with acute respiratory illness, March to June 2021.

Our data is aligned with previous research supporting the impact of social distancing on reducing the circulation of non-SARS-CoV-2 respiratory viruses, and that non-enveloped viruses such as rhinovirus, re-emerge initially as social distancing is eased, followed by other viruses. , The increase in detection of non-SARS-CoV-2 coronaviruses is in keeping with other reports of increased respiratory virus detections outside of the normal viral epidemiological cycles. These findings might have important implications for the complete relaxing of social distancing measures in the coming months and particularly on the forthcoming circulation of respiratory syncytial virus (RSV) and influenza viruses.

Declaration of Competing Interest

ART, NJB, SP, JP - None.

TWC reports non-financial support from QIAGEN, during the conduct of the study, personal fees and non-financial support from BioMerieux and BioFire LLC, and personal fees from Synairgen, Roche, Cidara Therapeutics, Janssen, and Randox Laboratories, outside of the submitted work.