The WHO met in September 2017 to decide the four viral flu strains that will be contained in next year’s flu vaccine.
WHO recommends that quadrivalent (4 strain) influenza vaccines for use in the 2018 southern hemisphere influenza season contain the following viruses: –
- A/Michigan/45/2015 (H1N1)pdm09-like virus
- A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus
- B/Phuket/3073/2013-like virus.
- B/Brisbane/60/2008-like virus, a B/Victoria lineage virus.
This represents one change from the 2017 flu vaccine with replacement of the A/Hong Kong/4801/2014 (H3N2)-like virus with an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus.
Once again there will be no Trivalent (3 strain) vaccine available in Australia in 2018
These WHO recommendations provide a guide to national public health and regulatory authorities and vaccine manufacturers for the development and production of influenza vaccines for the next influenza season. In contrast to many other vaccines, the viruses in influenza vaccines have to be evaluated and updated regularly because circulating influenza viruses continuously evolve. Recommendations are made in February/March for the following influenza season in the northern hemisphere and in September for the following influenza season in the southern hemisphere because approximately 6-8 months are needed to produce and approve vaccines.
source: http://www.who.int/influenza/vaccines/virus/recommendations/2018_south/en/
