Respiratory Viruses Surveillance Bulletin: Epidemiological Week 13, 2026

Overview

• Regional influenza positivity increased slightly from 8% in week 11 to 11% in week 13 of 2026, largely due to increases observed in Singapore and Viet Nam.  SARS-CoV-2 positivity remains below 5% in the Region (Figure 1). The predominant circulating influenza subtype is influenza B(Victoria), accounting for 87% of all detections (Figure 2).
• Media screening over the past two weeks has identified increased influenza activity in Australia, attributed to influenza A(H3N2) subclade K. Australia recorded its highest-ever number of deaths due to influenza in 2025, with a total of 1 738 deaths, and a further 63 deaths were reported in January 2026 [1][2]. The National Immunisation Program of Australia is expected to provide season influenza vaccines starting on April 2026 [2][3].