"University of California, Davis, researchers studying the 2009 H1N1 influenza virus, formerly referred to as "swine flu," have identified a group of immunologically important sites on the virus that are also present in seasonal flu viruses that have been circulating for years. These molecular sites appear to result in some level of immunity to the new virus in people who were exposed to the earlier influenza viruses.
One hallmark of this new influenza virus, according to the Centers for Disease Control and Prevention, has been the presence of pre-existing antibodies against the virus in about one third of H1N1 2009 patients over the age of 60, a phenomenon that suggested some levels of immunity may have existed to the new pandemic H1N1 virus."
One hallmark of this new influenza virus, according to the Centers for Disease Control and Prevention, has been the presence of pre-existing antibodies against the virus in about one third of H1N1 2009 patients over the age of 60, a phenomenon that suggested some levels of immunity may have existed to the new pandemic H1N1 virus."
