Twice a year, influenza experts meet to make recommendations on the composition of the next season's influenza vaccines. Next week, the group will determine which viruses they recommend be put in influenza vaccines for use in the northern hemisphere in 2010.
These consultations are held twice annually, one for the northern hemisphere (usually in February) and the other for the southern hemisphere (usually in September). The consultations are conducted to finalize analyses of influenza viruses that have been shared with WHO through a global network of national laboratories called GISN (Global Influenza Surveillance Network) and to make recommendations to WHO of which influenza viruses should be contained in influenza vaccine for the upcoming season. The analyses of viruses are complemented by available epidemiological and clinical information. These meetings will cover influenza viruses considered infectious for people and for which either developmental or commercial vaccines have been made. Such viruses include pandemic A(H1N1), seasonal influenza viruses, influenza A (H5N1) and influenza A(H9N2) viruses. These meetings also discuss serology studies of whether antibodies to current vaccines cover circulating viruses, and the availability of vaccine reassortant viruses and reference reagents. Based on all relevant considerations, the consultation provides a recommendation to WHO for composition of influenza vaccines.
In contrast to many other vaccines, the viruses in influenza vaccines are replaced frequently because circulating influenza viruses often mutate and change. Keeping up with these changes requires global virus sharing and monitoring.
Visit WHO's brief to learn more: http://www.who.int/entity/csr/disease/influenza/qanda_vaccinerechow.pdf
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