How are which viruses selected?
According to the Center for Disease Control, “141 national influenza centers in 111 countries conduct year-round surveillance for influenza and study influenza disease trends. These laboratories also send influenza viruses to the five World Health Organization (WHO) Collaborating Centers for Reference and Research on Influenza”.
“Twice a year, the World Health Organization (WHO) organizes a consultation with the Directors of the WHO Collaborating Centers and representatives of key national laboratories. They review the results of surveillance, laboratory, and clinical studies, and the availability of vaccine virus strains and make recommendations on the composition of the influenza vaccine. These meetings take place in February for making recommendations about the composition of the vaccine for the upcoming Northern Hemisphere’s seasonal influenza vaccine and in September for the Southern Hemisphere’s vaccine.”
Currently, our flu vaccines have been designed to attack a part of the flu virus that is able to rapidly change. This is why a new vaccine needs to be made each season. Scientists are making great progress with a vaccine that will attack an area that seems to be more consistent among more flu virus strains. This could result in ONE vaccine that is effective against MANY strains of the virus over a longer period of time (perhaps years; perhaps, eventually, over a lifetime) ... look out Influenza!