June 2, 2009 -- The world is "getting closer" to a full-scale swine flu pandemic, the World Health Organization (WHO) warns.
The official declaration of a pandemic alert -- triggered by widespread H1N1 swine flu beyond the Americas -- will come with a new severity rating, said Keiji Fukuda, WHO interim assistant director-general for health security and environment.
Swine Flu Outbreak: Get the Facts
Get the latest swine flu facts and information from WebMD, the CDC and other
public health agencies.
The WHO has been dragging its feet over declaring a worldwide pandemic to avoid causing undue alarm and to allow it time to develop specific guidance for different parts of the world.
When swine flu broke out, the world was already at phase 3 of its six-phase pandemic warning system. That was because the deadly H5N1 bird flu was infecting humans but not spreading from person to person.
When swine flu burst upon the world in April, the WHO rapidly raised its warning level from phase 4 and then to phase 5 as it became clear a flu virus new to humans was spreading easily -- and widely -- from person to person.
"Globally we believe we are at phase 5 but getting closer to phase 6," Fukuda said today at a news conference. "It is clear the virus continues to spread internationally. There are a number of countries that appear to be in transition [to widespread infections at the community level]. These countries include the U.K., Spain, Japan, Chile, and also Australia."
When the WHO finally does declare a global swine flu pandemic, it likely will rate the severity of the disease as moderate, not mild or severe.
"It is fair to call the situation moderate," Fukuda said. "We know this infection can be fatal in a number of individuals. This includes people who have some underlying medical conditions and it includes women who are pregnant -- but it also includes people who are perfectly healthy. So we do have some hesitation calling such an infection mild."
Fukuda noted that severity does not solely depend on the virulence of the virus.
"Severity is not just a quality of the virus and its ability to harm people, but a combination of that virulence and the vulnerability of populations -- how well off they are in terms of chronic conditions and poverty and malnourishment," he said. "And it's also a matter of the resilience of nations, how well they are able to cope with diseases."
Fukuda said the WHO's rating would be flexible in order to change as the pandemic becomes more or less severe.
Meanwhile, all eyes are on the Southern Hemisphere -- particularly Chile and Australia -- as swine flu hits that part of the world just as it's entering normal flu season. At this early point in their flu season, Fukuda said, nearly all flu cases appear to be swine flu and not seasonal flu.
"We will look carefully to see if the kind of illness typical of flu is seen in the Southern Hemisphere, and particularly at which age groups," Fukuda said. "Will there be a change in the number of people who develop serious illness? Will there be a change in the virus itself? We expect the virus to drift, but does that really lead to any changes in the behavior of the virus, and to the antigenicity of the virus [that would affect vaccine development]? We will be monitoring that carefully."