Exposure to past plagues gave swine flu immunity to sixtysomethings. People in their 60s and over are relatively immune to swine flu because it is similar to H1N1 viruses that circulated before 1943, a group of researchers said Friday. [News Source]

Mix and match. Scientists have been looking at which animal species might act as reservoirs for influenza viruses and - worse, from the human point of view - which might act as “mixing vessels” in which new strains of virus are generated. [News Source]

Easing H1N1 pandemic may let in new flu viruses. The declining wave of pandemic H1N1 flu is likely to be followed by new, unknown strains of seasonal flu which health authorities must watch carefully to devise protection measures, European flu experts said on Friday. [News Source]