Different flu vaccines? Southern vs Northern hemisphere
October 15th, 2025The vaccines for southern hemisphere 2025 and northern hemisphere 2025/6 cover basically the same influenza strains.
2025 Southern
The egg-based trivalent influenza vaccines contain the following three viral strains:
Cell-based trivalent influenza vaccines contain the following three viral strains:
Quadrivalent egg- or cell culture-based or recombinant vaccines contain the following B/Yamagata lineage component:
Source
https://www.tga.gov.au/resources/publication/publications/2025-seasonal-influenza-vaccines
Egg-based vaccines
• an A/Victoria/4897/2022 (H1N1)pdm09-like virus;
• an A/Croatia/10136RV/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
• an A/Wisconsin/67/2022 (H1N1)pdm09-like virus;
• an A/District of Columbia/27/2023 (H3N2)-like virus; and
• a B/Austria/1359417/2021 (B/Victoria lineage)-like virus.
• a B/Phuket/3073/2013 (B/Yamagata lineage)-like virus.
I recommend the CELL based influenza vaccine rather EGG based, as the evidence supports that cell based vaccines are slightly more effective than egg based ones.
Optimal protection offered by the influenza vaccine lasts for 3–4 months following vaccination; after this, the level of protection begins to decrease.
