WEDNESDAY, June 3, 2009 (HealthDay News) -- With more cases of the H1N1 swine flu surfacing in the Southern Hemisphere and outside North America, the World Health Organization is weighing whether to declare a global pandemic.
While the vast majority of infections and deaths have occurred in Mexico (the source of the outbreak) and the United States, person-to-person transmission in now being reported in countries such as Australia (501 cases) and Chile (313 cases), as well as Great Britain, Spain and Japan, according to published reports.
"We still are waiting for evidence of really widespread community activity in these countries, and so it's fair to say that they are in transition and are not quite there yet, which is why we are not in phase 6 yet," WHO flu chief Dr. Keiji Fukuda said during a Tuesday press conference at the agency's headquarters in Geneva, Switzerland.
Phase 6 is the highest alert on WHO's scale, representing a global epidemic. In terms of the geographic spread of swine flu, the world is "at phase 5 but getting closer to phase 6," Fukuda said, the Associated Press reported.
The WHO is debating whether to add a second measure that indicates how dangerous the H1N1 swine flu virus is -- rather than just how widespread -- after several countries expressed concerns that declaring a global pandemic could cause mass confusion and panic even though it's still not clear how dangerous the virus will be, the news service said.
To date, the virus has caused 19,273 cases of infection in 66 countries, but just 117 deaths, 97 of them in Mexico, the WHO reported Wednesday.
Since the outbreak started in April, health officials in the United States have said that infections have been mild for the most part, and most patients recover fairly quickly. Testing has found that the H1N1 virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza.
The U.S. Centers for Disease Control and Prevention was reporting Wednesday a total of 11,054 cases in all 50 states and the District of Columbia and Puerto Rico, including 17 deaths. The agency said that confirmed cases of H1N1 swine flu represent about one in 20 of actual cases, bringing the total probable number of cases in the United States to about 200,000.
During the next few months, CDC scientists will be looking to see if the swine flu virus mutates or becomes resistant to antiviral medications, or is more easily spread among people. The flu season is winding down in the Northern Hemisphere but is just beginning in the Southern Hemisphere.
U.S. health officials have said there's no way to tell now if the H1N1 virus will be more virulent when -- and if -- it returns to the Northern Hemisphere with the approach of winter.
What has been different about the swine flu outbreak in the United States so far is that activity picked up late in the typical flu season, Tom Skinner, a CDC spokesman, said during a Monday press conference. "What was unusual was that in late March into April and late May we saw activity at a higher-than-expected level," he said.
Some older people may have partial immunity to the H1N1 swine flu virus because of possible exposure to another H1N1 flu strain that circulated prior to 1957, according to the CDC.
A vaccine for the swine flu virus could be ready by October, if research and testing proceed on pace this summer. Candidate viruses have been shipped to vaccine manufacturers, agency officials said.
It's still not clear whether a swine flu vaccine is needed. Any decision to move forward would be based on several factors, including the severity and spread of the virus and whether there's a safe and effective vaccine, the CDC has said.
Cases of H1N1 swine flu infection have not been spread evenly across the country. For instance, the flu has shut many schools in New York City, but the virology lab at the University of California, San Francisco, has not found a positive flu sample in the Bay Area in weeks, The New York Times reported.
For more on swine flu, visit the U.S. Centers for Disease Control and Prevention.