Decline of Influenza and Respiratory Viruses With COVID-19 Public Health Measures

OBJECTIVE We evaluated the incidence of influenza and non-influenza respiratory viruses (NIRVs) pre-/post-implementation of public health (PH) measures aimed to decrease COVID-19 transmission using population-based surveillance data. We hypothesized that such measures could reduce the burden of respiratory viruses (RVs) transmitting via the same routes. PATIENTS AND METHODS An interrupted time-series analysis of RV surveillance data in Alberta, Canada from May 2017 – July 2020 was conducted. The burden of influenza and NIRVs before and after intervention initiation at week 11, 2020 was compared. The analysis was adjusted for seasonality, over-dispersion, and autocorrelation. RESULTS During the study period, an average of 708 and 4056 weekly respiratory multiplex molecular panels were conducted pre-/post-intervention respectively. We found significant reductions in test positivity rates in the post-intervention period for influenza (-94.3%; 95% CI -93.8 to 97.4%, p CONCLUSION The implementation of COVID-19 PH measures likely resulted in reduced transmission of common RVs. While drastic lockdowns are unlikely to be required given widespread COVID-19 vaccination, targeted implementation of such measures can lower RV disease burden. Studies to evaluate relative contributions of individual interventions are warranted.