Surveillance trends for SARS-CoV-2 and other respiratory pathogens among U.S. military health system beneficiaries, 27 September 2020–2 October 2021.

Laboratory-based respiratory pathogen surveillance for SARS-CoV-2 and other respiratory pathogens was conducted in the 2020-2021 surveillance season among U.S. Military Health System (MHS) beneficiaries through the Department of Defense Global Respiratory Pathogen Surveillance Program (DoDGRPSP). Sentinel and participating sites submitted 96,660 specimens for clinical diagnostic testing. A total of 12,282 SARS-CoV-2 positive cases were identified, and 7,286 of the associated viruses were successfully sequenced. Two overlapping waves of SARS-CoV-2 activity were observed during the season. The B.1.1.7 (Alpha) lineage was dominant during February 2021 through May 2021. By July 2021, and continuing through the rest of the season, B.1.617.2/AY.x (Delta) lineage predominated and by September 2021 comprised 100% of identified SARS-CoV-2 lineages. The emergence of SARS-CoV-2 coincided with substantial reductions in the circulation of seasonal influenza viruses and most other non-SARS-CoV-2 respiratory pathogens. A total of 4,426 non-SARS-CoV-2 respiratory pathogens were identified, including 71 influenza. Of the 71 influenza positives, 64 were successfully sequenced. The majority of influenza strains sequenced belonged to influenza A(H3N2) clades 3C.2a1b.2a2. The most common non-SARSCoV-2 respiratory pathogen detected was rhinovirus/enterovirus (n=3,058).