1897. The Decline of Respiratory Viruses During the SARS-CoV-2 Pandemic: Public Health Interventions vs. Viral Competition?


 
 
 With the spread of the SARS-CoV-2 pandemic in 2020 and the attendant global precautions such as masking, travel restrictions and social distancing, the WHO FluNet data indicated a decline in flu rates. The CDC data for the 2020-2021 season showed the same decline in US flu as well as other respiratory viruses. Two hypotheses to explain the observed phenomenon are the impact of non-pharmaceutical interventions (NPI) to prevent SARS-CoV-2 infection and suppression of other respiratory viruses by SARS-CoV-2 through a form of resource competition.
 
 
 
 We conducted a study using the EPIC Slicer Dicer analytics tool and the Yale Internal Medicine COVID-19 Database to retrieve data from the Yale New Haven Health System (YNHHS). We tabulated the total number of positive and negative tests for SARS-CoV-2 and a panel of respiratory viruses from September 2, 2018 to April 30, 2022 to cover pre- and peri-pandemic periods. These results were divided into three age groups: ≤12, 13-59, and ≥60. Epidemic curves of each virus with respect to each other, the season, and the introduction of NPIs were constructed to help differentiate between the two hypotheses.
 
 
 
 Pre-pandemic data from 09/2018 to 02/2020 revealed seasonal spikes in influenza A and B with 254 positive weekly influenza A/B tests from 11/2018 to 02/2019 for a positivity rate of 7.97% and 481 positive weekly tests (10.53% positivity rate [PR]) from November 2019 to February 2020. There were only 0.35 positive weekly influenza A/B tests (0.05% PR) from 11/2020 to 02/2021 with 2018 positive weekly tests (6.45% PR) for SARS-CoV-2 over the same period. From 11/2020 to 02/2021, there were 56 positive weekly influenza A/B tests (1.44% PR) and 4347 positive weekly SARS-CoV-2 tests (10.35% PR). From 07/2021 to 11/2021, there was an increased rate of positive RSV tests (82 per week, 15.76% PR) and rhinovirus tests (58 per week, 18.73% PR). There were 803 positive weekly tests (2.53% positivity rate) for SARS-CoV-2 over this same period.
 
 
 
 Since the start of the SARS-CoV-2 pandemic, the number of positive tests for influenza A/B and seasonal respiratory viruses have not reached pre-pandemic levels across the YNHHS. However, rates of influenza and other respiratory viruses have increased since the relaxation of NPIs.
 
 
 
 All Authors: No reported disclosures.
