The initial fear that swine flu is a totally new virus that your immune system isn’t equipped to handle turns out to be pure hype. According to a new study, immune systems that have previously had contact with flu viruses recognize H1N1 and deal with it the same way, by trying to attack the virus in the bloodstream and in infected cells. That’s why swine flu hasn’t been such a killer—the severity of infections has been about on par with a seasonal flu.
The researchers used a major flu database to examine how antibody cells reacted to the virus. Only 17% of B cells—which prevent infection—recognized H1N1, explaining its rapid spread. But 69% of T cells, which fight the virus after infection, spotted and attacked it. "We provide an explanation for observations that the disease severity is not greater," one researcher told HealthDay. "Maybe it is even less than ordinary seasonal flu." (Read more swine flu stories.)