Phylogeography of SARS-CoV-2 Omicron sublineages detected in asymptomatic blood donors during third epidemiological wave in Mato Grosso, Midwestern Brazil.

Emerging infectious disease agents represent pathogens that may evade current screening protocols while posing significant transfusion transmission risks regionally. This study investigated the prevalence of SARS-CoV-2 and other respiratory viruses among 633 blood donors at the MT-Hemocentro from November 2021 to February 2023. Nucleic acid obtained from nasopharyngeal swabs were tested by RT-qPCR for SARS-CoV-2, RSV, FLU-A, and FLU-B. Serum from positive samples was also tested for nucleic acid. The prevalence of SARS-CoV-2 was 6.48 % (41/633); 2 of the 41 blood donors had SARSCoV-2 detectable in their serum. All positive samples were collected between January 2022 and March 2023, coinciding with the third epidemic wave in Brazil; 97.6 % of these SARS-CoV-2-positive donors were vaccinated with at least two doses. SARS-CoV-2 genomes recovered from six nasopharyngeal samples were classified into BA.1.1.1, BA.1.14.1, BA.2, BA.5.1, BA.5.2.1 sublineages. Phylogeographic analysis across Brazil's five regions revealed that the Northeast acted as the main exporter of Omicron sublineages, while the South and Southeast regions were more frequently importers.