Outbreak of Influenza and SARS-CoV-2 at the Armed Forces of the Philippines Health Service Education and Training Center, September 25–October 10, 2023

• Published in: MSMR (U.S. Army Center for Health Promotion and Preventive Medicine, Executive Communications Division) Executive Communications Division), 2024-05, Vol.31 (5), p.9-15
• Main Authors: Velasco, John Mark, Valderama, Maria Theresa, Diones, Paula Corazon, Leonardia, Susie, Alcantara, Simon, Joonlasak, Khajohn, Chinnawirotpisan, Piyawan, Manasatienkij, Wudtichai, Klungthong, Chonticha, Arellano, Errol Roy, Osia, Carrol Mae, Magistrado-Payot, Joy, Fajardo, Paul, Navarro, Fatima Claire, Wuertz, Kathryn McGuckin, Farmer, Aaron
• Format: Article
• Language: English
• ISSN: 2158-0111; 2152-8217

In the last week of September 2023, a surge of influenza-like illness was observed among students of the Armed Forces of the Philippines (AFP) Health Service Education and Training Center, where 48 (27 males and 21 females; age in years: mean 33, range 27-41) of 247 military students at the Center presented with respiratory symptoms. Between September 25 and October 10, 2023, all 48 symptomatic students were evaluated with real-time reverse transcription polymerase chain reaction and sequencing for both influenza and SARS-CoV-2. Thirteen (27%) students were found positive for influenza A/H3 only, 6 (13%) for SARS-CoV-2 only, and 4 (8%) were co-infected with influenza A/H3 and SARS-CoV-2. Seventeen influenza A/H3N2 viruses belonged to the same clade, 3C.2a1b.2a.2a.3a, and 4 SARS-CoV-2 sequences belonged to the JE1.1 lineage, indicating a common source outbreak for both. The influenza A/H3N2 circulating virus belonged to a different clade than the vaccine strain for 2023 (3C.2a1b.2a.2a). Only 4 students had received the influenza vaccine for 2023. In response, the AFP Surgeon General issued a memorandum to all military health institutions on October 19, 2023 that mandated influenza vaccination as a prerequisite for enrollment of students at all education and training centers, along with implementation of non-pharmaceutical interventions and early notification and testing of students exhibiting influenza-like-illness.