H1N1 Pandemic - WHO raises pandemic threat level

World health officials have raised the level of alert about a possible swine flu pandemic, since the virus seems to be spreading regularly from person to person.

The World Health Organization (WHO) upgraded the alert in an http://kenbudd.blogspot.com/2009/04/h1n1-story-behind-pandemic.html in Geneva on Monday evening.

"It's a significant step towards pandemic influenza, but it is a phase that says we are not there yet," said Keiji Fukada of the WHO. "A pandemic is not considered inevitable at this time."

The new H1N1 influenza virus has struck hundreds of people in Mexico, where at least 18 have died, and several dozen people in the US (see Deadly new flu virus in US and Mexico may go pandemic). In the last couple of days, confirmed cases have also been found in Canada, Spain and Scotland.

Six-point scale

WHO officials decided that the new cases and infection patterns warranted increasing their pandemic warning level from 3 to 4, on a six-point scale.

Ever since the scale went into use in 2005, it has stayed at 3 – indicating that most cases of an emergent influenza virus are caused by animal-to-human transmission.

At 4, the infection is spread primarily from human to human. At 5, human-to-human transmission is occurring at multiple geographic locations; while 6 represents an all-out pandemic, which occurs when a virus is new, causes severe disease, and transmits easily enough to be sustained.

Researchers are still studying how efficiently the virus spreads. "The situation is very fluid and it is possible we could move to a higher phase shortly," Fukada said.