Flu vaccination this year 2025 :
Start the flu season now in Thailand and you should have all 4 strains of flu vaccination now.
Influenza Vaccine Strain Recommendations for 2025 by WHO
The World Health Organization (WHO) has announced the recommended influenza vaccine strains for the 2025 influenza season, with separate recommendations for the Southern Hemisphere and Northern Hemisphere. These recommendations are based on the analysis of global influenza virus surveillance data by the WHO Global Influenza Surveillance and Response System (GISRS) and are critical for ensuring vaccine effectiveness against circulating strains .
Southern Hemisphere (2025 Season)
For the 2025 Southern Hemisphere influenza season, the WHO recommends the following strains for trivalent vaccines:
Egg-based vaccines:
A/Victoria/4897/2022 (H1N1)pdm09-like virus
A/Croatia/10136RV/2023 (H3N2)-like virus
B/Austria/1359417/2021 (B/Victoria lineage)-like virus
Cell culture-, recombinant protein-, or nucleic acid-based vaccines:
A/Wisconsin/67/2022 (H1N1)pdm09-like virus
A/District of Columbia/27/2023 (H3N2)-like virus
B/Austria/1359417/2021 (B/Victoria lineage)-like virus
For quadrivalent vaccines, the B/Yamagata lineage component remains unchanged:
B/Phuket/3073/2013 (B/Yamagata lineage)-like virus .
Northern Hemisphere (2025-2026 Season)
The WHO has not yet finalized the recommendations for the 2025-2026 Northern Hemisphere influenza season. However, a meeting is scheduled for February 2025 to analyze global influenza activity and determine the vaccine composition. This meeting will involve experts from WHO Collaborating Centres, regulatory agencies, and vaccine manufacturers .
Key Changes and Rationale
H3N2 Update: The H3N2 component for the Southern Hemisphere has been updated to A/Croatia/10136RV/2023 (H3N2)-like virus to reflect the latest circulating strains .
B/Yamagata Exclusion: The B/Yamagata lineage has not been detected in circulation since March 2020, leading to a shift toward trivalent vaccines in many regions. However, quadrivalent vaccines still include this component for regions where it remains in use .