TUESDAY, April 6 (HealthDay News) The traditional seasonal flu vaccine may have increased the risk of infection with pandemic H1N1 swine flu, according to the results of four new studies by Canadian researchers.
In one study, the researchers used an ongoing sentinel monitoring system to assess the frequency of prior vaccination with the seasonal flu vaccine in people diagnosed with H1N1 swine flu in 2009 compared to people without swine flu. The researchers found that seasonal flu vaccination was associated with a 68 percent increased risk of getting swine flu...