The Centers for Disease Control held a press briefing this morning at 1 p.m. EST about the "novel H1N1" virus. Anne Schuchat, interim deputy director for the Science and Public Health Program, and influenza expert Nancy Cox gave updated statistics: there are 226 confirmed cases in the U.S. in 30 states, up from 21 yesterday. The median age of cases is 17 years, quite young and a very different pattern from seasonal flu. It's possible that older people may have some protection from exposure to previous strains, or to flu vaccines, and the CDC is looking at that, especially in relation to who might first receive a vaccine.
Development of a vaccine is well underway, but there is no ETA for it at this time. The CDC really wants to have one ready and in place in time for the fall/winter flu season.
The CDC is amazed by the Internet interest in the virus. It is getting 8 million visitors to its website (pandemicflu.gov) per day. There has been one Tweet per second on Twitter about H1N1. Said the spokeswoman, with no apparent irony, "We really appreciate the viral spread of our educational messages" about H1N1.
During the press question and answer session, the CDC explained once again why it is calling the virus "novel H1N1" instead of "swine flu": because it is a version of something we have never seen before (whereas "swine flu" is generic). In response to a reporter's question, Cox tried (presumably for the nth time) the difficult and complex process of how flu viruses swap pieces of their genetic code with their hosts. Since pigs are susceptible to both avian and human viruses, they are a "wonderful mixing vessel" for influenza viruses in new ways. (New Scientist explains this process in detail.) But as to where this little porcine petri dish might be located, that's impossible to know.
"Our working hypothesis was that the reassortment happened in pigs," she said. But "the ancestral origin of the genes doesn't have an impact on our statement that you can't get the novel H1N1 virus from eating pork."
In regard to big public U.S. gatherings such as graduations, etc, the CDC does not think canceling them makes sense: "We really want people who are sick to stay home, and not go, and we want the people who do go to remember to take steps like wash their hands."