New research by a UC Davis scientist and a UC Cooperative Extension specialist has found that some senior citizens already have a level of immunity to H1N1 flu, formerly known as Swine flu. The finding may explain why the 2009 H1N1-related symptoms have been generally mild, according to a UC Davis news release distributed to the media yesterday.

"The more you're exposed to viruses that can stimulate all types of immune response, the better protected you're likely to be," the Sacramento Bee quoted UCCE specialist and study co-author Carol Cardona in a story about the findings. "There does seem to...