Impact of non-pharmaceutical interventions on circulating respiratory viruses during the COVID-19 pandemic in Turkey

BACKGROUND: Non-pharmaceutical interventions (NPIs) applied to limit the SARS-CoV-2 pandemic also affect the circulation and seasonal characteristics of other respiratory viruses. OBJECTIVES: Assess the impact of NPIs on the spread and seasonal characteristics of non-SARS-CoV-2 respiratory viruses and examine viral respiratory co-infections. DESIGN: Retrospective cohort SETTING: Single center in Turkey. PATIENTS AND METHODS: Syndromic multiplex viral polymerase chain reaction (mPCR) panel results of patients admitted to the Ankara Bilkent City Hospital with symptoms of acute respiratory tract infection between April 1, 2020 and October 30, 2022 were evaluated. Two study periods before and after 1 July 2021, when the restrictions were discontinued, were statistically analyzed and compared to determine the effect of NPIs on circulating respiratory viruses. MAIN OUTCOME MEASURES: Prevalence of respiratory viruses as determined by syndromic mPCR panel. SAMPLE SIZE: 11300 patient samples were evaluated. RESULTS: At least one respiratory tract virus was detected in 6250 (55.3%) patients. Of these, at least one respiratory virus was detected in 5% in the first period (between April 1, 2020 and June 30, 2021, when NPIs were applied), and in 95% in the second period (between July 1, 2021 and October 30, 2022, when NPIs were relaxed). After the removal of NPIs, there was a statistically significant increase in hRV/EV, RSV-A/B, Flu A/H3, hBoV, hMPV, PIV-1, PIV-4, hCoV-OC43, PIV-2 and hCoV-NL63 (P<.05). In the 2020-2021 season, when strict NPIs were applied, all respiratory viruses evaluated did not have the usual seasonal peak and there were no seasonal influenza epidemics during this period. CONCLUSIONS: NPIs resulted in a dramatic decrease in the prevalence of respiratory viruses and notable disruption of seasonal characteristics. LIMITATIONS: Single-center study and retrospective. CONFLICT OF INTEREST: None.