WHO calls for Souther Hemisphere flu vaccine to use same strains as last year

The World Health Organization recently acknowledged a run of stability in the makeup of seasonal influenza vaccines when it recommended using the same three strains in next year’s Southern Hemisphere vaccine that are in the current Northern Hemisphere vaccine.

The same three strains were used in last year’s Southern Hemisphere vaccine. The WHO has seen little evidence that changes in the circulating flu strains would make the current vaccine a poor match to the near future’s prevalent strains, according to CIDRAP News.

The WHO recommended keeping the pandemic 2009 strain for the A/H1N1 portion of the vaccine’s makeup. In addition, it recommended a Perth 2009 strain of A/H3N2 and a Brisbane 2008 strain of influenza B for the remainder of the vaccine.

This recommendation is the third time in a row that these three strains have been chosen to makeup the Southern Hemisphere’s seasonal influenza vaccine. WHO experts recommended the strains in September to allow for the vaccine to be grown in eggs. Northern Hemisphere recommendations are usually made every February.

According to the WHO, the vast majority of 2009 H1N1 cases have remained susceptible to Tamiflu. Most of the resistant isolates have been associated with its use, CIDRAP News reports. The United States, the United Kingdom and Japan, however, have seen an increased number of isolates that showed exposure to treatment with the drug.