Vaccine researchers warn of return of 1957 flu

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Three vaccine researchers from the National Institutes of Health say that influenza A/H2N2 viruses, which caused the flu pandemic in 1957 and 1958, might return and lead to a pandemic similar to the H1N1 epidemic in 2009.

In a commentary published in this week’s issue of Nature, the scientists assert that the threat is large enough to warrant creating a preemptive vaccination strategy, CIDRAP News reports. Since the H2N2 viruses have circulated in pigs and birds but not humans for 50 years, the scientists worry about lack of immunity to the subtype.

They reference the 1918 H1N1 virus that had a similar hemagglutinin component in pigs for over a century, which was “poised to cross back into humans and cause a new pandemic when broad protective human immunity had waned,” the article said.

The H2N2 virus continued to circulate after 1958 until it was displaced by the H3N2 virus in 1968, which has circulated ever since. H2N2 strains have not been found in humans for many years.

The authors conducted their study between 2003 and 2007, testing 90 people for immunity to H2N2. “Our study suggests that people under 50 have little or no immunity, and resistance dramatically increases for those over 50,” the authors wrote. “The low mutation rate for H2N2, and evidence of waning human immunity, make it likely that an H2N2 pandemic could arise from animals.”

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