The vaccine protects against three types of flu virus and experts meet twice a year to decide which strains should be included. Based on continuous year-round global surveillance, the WHO advises as to which strains will be the most likely to cause influenza in the coming season, so as to ensure that these strains are included in the vaccine.
The World Health Organisation’s decision to change two of the flu strains for the 2012/2013 season is the first time since 2010 that new strains have been proposed.
Back in 2010, the A/H1N1 virus – which caused the 2009 global flu pandemic – was included in the seasonal flu vaccine. It will still be included next winter, along with two others (A/Perth/H3N2 and B/Wisconsin). (More details)
The decision suggests the vaccine currently in use needs to be updated because it is not protecting against some of the upcoming strains of influenza.
The World Health Organisation’s recommendation comes as European health authorities suggested flu epidemics in some European countries may be set to peak.
The flu season in Europe has arrived later than usual this year and the number of cases had been climbing for several weeks.
Read more about how the WHO selects which flu strains to include in the vaccine