Which vaccine formulation to use – Northern or Southern Hemisphere?

Vaccine formulation map
Vaccine formulation

From an antigenic evolution perspective, there is no evidence to suggest the need for a 3rd recommendation for vaccine composition specifically for the tropics and subtropics, and the most recent WHO influenza virus vaccine recommendation should be used, independent of the hemisphere in which the country is situated.

Countries are encourage to strengthen surveillance and share viruses with WHO Collaborating Centers of Global Influenza Surveillance and Response System for analysis of antigenic and genetic similarity with both the NH and SH vaccine formulation of the respective season, to determine which vaccine formulation has a better antigenic correspondence with currently circulating viruses.