Military operations involve the global movement of personnel and equipment, increasing the risk of spreading infectious pathogens such as SARS-CoV-2. Given the continuous engagement of the Polish Armed Forces in overseas operations, an active surveillance program targeting Variants of Concern (VOC) of SARS-CoV-2 was implemented among military personnel. Screening using RT-qPCR tests was conducted on 1699 soldiers between November 2021 and May 2022. Of these, 84 SARS-CoV-2 positive samples met the criteria for whole genome sequencing analysis and variant identification. Whole genome sequencing was performed using two advanced next-generation sequencing (NGS) technologies: sequencing by synthesis and nanopore sequencing. Our analysis revealed eleven SARS-CoV-2 lineages belonging to 21K, 21L, and 21J. The predominant lineage was BA.1.1 (57% of the samples), followed by BA.1 (23%) and BA.2 (6%). Notably, all identified lineages detected in post-deployment screening tests were classified as VOC and were already present in Poland, showing the effectiveness of the Military Sanitary Inspection measures in mitigating the COVID-19 spread. Pre-departure and post-mission screening and isolation successfully prevented SARS-CoV-2 VOC exportation and importation. Proactive measures are vital in minimizing the impact of COVID-19 in military settings, emphasizing the need for continued vigilance and response strategies.
Keywords: COVID-19; SARS-CoV-2; genomic epidemiology; military; outbreak; variants.