Respiratory Viruses Surveillance Bulletin: Epidemiological Week 43, 2026

Overview

• Regional influenza positivity decreased from 14% in week 41 to 12% in week 43 of 2026. SARS-CoV-2 positivity increased from 1% in week 41 to 2% in week 43 of 2026 (Figure 1).
• The predominant circulating influenza subtype is influenza A(H1N1)pdm09, accounting for 38.8% of all detections, followed by influenza A(H3) (35.9%) and influenza B(Victoria) (24.1%) (Figure 2).
• Influenza activity remained elevated in most countries and areas in all transmission zones, despite decreased activity during the reporting period. In particular, positivity remained above 50% in Viet Nam.
• Reported influenza-like illness (ILI) cases has decreased in majority of the Pacific Island Countries and areas. No unusual epidemiological patterns or signals of severity have been identified. While the overall regional risk remains low, influenza activity is expected to continue in the coming weeks and will likely result in additional cases and some localised pressure on health services.