“Governments should start vaccinations against a lethal strain of the influenza virus circulating in birds and pigs’ Vaccine Research Centre of the US National Institutes of Health
‘The researchers draw a number of parallels between the H1N1 and H2N2 viruses. For example, they have both caused pandemics: from 1957 to 1968, an H2N2 strain caused 1–4 million deaths worldwide. Like the 1918 strain, the H2N2 virus has not circulated in humans for several decades but continues to do so among birds and pigs.
To examine people’s levels of immunity to this class of virus, between 2003 and 2007 the researchers tested stored blood samples for antibodies against H2N2 strains in a small cohort of 90 people in the US. The researchers admit that ideally the test needs to be repeated in several thousand individuals, but say their study suggests that people under the age of 50 have little or no immunity to H2N2, and immunity is far stronger in people over 50 (as was also the case for H1N1).
The researchers argue that governments should plan a pre-emptive vaccination programme to prevent the re-emergence of H2N2 in humans, perhaps based on the vaccine against H2N2 licensed for use against the 1957-68 pandemic.