"While reports from Mexico are -- appear to be encouraging, and some are cautiously optimistic, we can't afford to let down our vigilance," the Centers for Disease Controls's Rear Admiral Anne Schuchat said today. "We have information that this novel virus continues to spread, with increasing cases and increased states affected."
School closures, asking individuals who feel sick to stay at home and hand washing are all preventive elements, officials have said.
In the United States, there are 160 confirmed cases in 21 states, Schuchat said. One person has died from the flu in this country, a toddler who died last month in Texas. In Mexico, 16 people have died.
"The majority of cases don't have direct contact with Mexico. They didn't travel to Mexico," Schuchat said. "It is much more likely that people are getting this particular infection now from somebody ... within their own communities. You know, we do think that there's sustained transmission here in the U.S. in several areas."
According to the World Health Organization, a total of 16 countries now have at least one case of the disease, also known as H1N1 flu, and the overall number of confirmed cases has risen to more than 650.
"This is a new strain of the flu virus, and because we haven't developed an immunity to it, it has more potential to cause us harm," President Obama said in his weekly address today. "Unlike the various strains of animal flu that have emerged in the past, it's a flu that is spreading from human to human. This creates the potential for a pandemic, which is why we are acting quickly and aggressively."
But though there has been "no evidence of sustained community spread outside North America," Dr. Michael J. Ryan, the director of the WHO's global alert and response team, said today that he "would still propose that a pandemic is imminent, because we are seeing the disease spread."
On Wednesday, the WHO upgraded the pandemic alert level to phase five, which "is a strong signal that a pandemic is imminent," according to the organization's guidelines. During the current phase, officials around the world have stepped up preparations for a potential pandemic and increased communication and coordination.
The next level, six, indicates that "a global pandemic is under way," the guidelines say.
"At this point we have to expect that phase six will be reached, we have to hope that it is not reached," Ryan said. But he added that the term pandemic only refers to the geographic spread of a disease, not its severity.
Ryan spoke at a briefing earlier today at the WHO headquarters in Geneva. He said the organization is dispersing 2.4 million courses of antiviral medication to 72 developing countries, including Mexico.
Obama said today that the United States will continue "investing in every resource necessary to treat this virus and prevent a wider outbreak."
"The good news is that the current strain of H1N1 can be defeated by a course of antiviral treatment that we already have on hand," he continued, adding that the nation's stockpile of such medicines had 50 million courses of treatment at the beginning of the week, and that a quarter of the medicine has been distributed to states.