H1N1INFLUENZAVIRUS.US

Seasonal influenza viruses are type B viruses; they only infect humans and usually cause mild disease in young healthy people. … H1N1 is a type A virus, which can infect other animals, such as pigs and birds, as well as humans…. There are also at least 100 different ‘common cold’ viruses that can cause similar symptoms, but generally, symptoms of the flu occur more suddenly, a …

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The Biology of Influenza and Vaccination