WHO switches H1N1 in Southern Hemisphere flu vaccine

World Health Organization (WHO) vaccine advisors today recommended changing only the 2009 H1N1 component for the Southern Hemisphere’s 2017 flu vaccine, the first change in the H1N1 component since the former pandemic virus became a globally circulating seasonal flu strain. The newly recommended H1N1 vaccine strain, called A/Michigan/45/2015 replaces the longstanding A/California/7/2009 and is recommended to improve protection against two subclades that have emerged over the past season. However, the seasonal flu vaccines for the Northern Hemisphere, based in the WHO group’s recommendation last February, still contain the A/California/7/2009 vaccine strain. During the Northern Hemisphere’s previous flu season, some flu experts in Europe, which experienced a late flu season, raised questions about whether newly emerging H1N1 subgroups were dampening the effect of the vaccine. The WHO group said in its report today that an analysis of 2009 H1N1 samples collected from February to August showed that the vast majority fell into clade 6B,...