Effect of non-pharmaceutical interventions on the incidence of respiratory viruses at a tertiary cancer care center

BACKGROUND: In March 2020, nonpharmaceutical interventions (NPIs) including face coverings and social distancing were adopted to curb the spread of SARS-CoV-2. Over the course of the pandemic, adherence to these NPIs has varied and eventually became optional in most non healthcare settings. We investigated the impact of relaxation of NPI on the incidence of respiratory viruses other than SARS-CoV-2 at a tertiary cancer care hospital. METHODS: This was a retrospective cohort study of respiratory viral panel results performed at between 08/01/2014–07/31/2022. Only one viral target result per patient per year was included. Poisson regression models were used to compare 2019–2020, 2020–2021, and 2021–2022 incidence of respiratory viruses to those of 2014–2019. Interrupted time series analysis was performed using autoregressive integrated moving average models in order to compare expected and observed positivity rates. RESULTS: A large reduction in the odds of testing positive for a respiratory virus was observed for most respiratory viruses when comparing results from 2019 to 2020 group to the corresponding period in 2014–2019. Subsequent seasons showed ongoing reductions in the odds of testing positive while slowly increasing over time back toward pre-pandemic levels. A time interrupted series analysis showed that the monthly positivity rate for all respiratory pathogens were reduced after 03/01/2020, when compared to the expected values forecast, except for adenovirus. CONCLUSIONS: This study provides valuable data that could be used to guide public health practices and support the efficacy of NPIs in curtailing the spread of novel and endemic respiratory viruses.