Vaccines for the north and south

THE formulations for flu vaccines for the northern hemisphere and southern hemisphere are determined separately and may be different every year.

As a flu vaccine takes about six months to manufacture, the World Health Organisation’s Global Influenza Surveillance Network (GISN) – a network that monitors circulating influenza strains in laboratories all over the world – will meet every February to recommend virus strains to be included in the influenza vaccine for the northern hemisphere.