GENEVA The head of the World Health Organization will increase the pandemic flu alert level to 5, the second highest level, WHO sources said Wednesday.
Director-General Margaret Chan is expected to make the announcement at a 10 p.m. (2000 GMT) press briefing about the swine flu outbreak at the WHO's Geneva headquarters.
"Things are moving fast," one source said.
Another said Chan would increase the alert by one step, from 4 to 5, in response to the spreading virus that has killed as many as 159 people in Mexico and spread to the United States, Canada, Europe, Israel, and New Zealand.
"I don't think it will be 6," that source said.
According to the WHO's pandemic flu response guidelines, a phase 5 alert is called when there is human-to-human spread of virus in at least two countries in one region.
"While most countries will not be affected at this stage, the declaration of Phase 5 is a strong signal that a pandemic is imminent and that the time to finalize the organization, communication and implementation of the planned mitigation measures is short," the document reads.
Chan's move to raise the pandemic level, set to occur without another formal emergency committee meeting, follows intensive consultations with experts and analysis of the spreading virus within and from Mexico, sources said.
The change in level would put governments on alert about the need to stockpile antiviral drugs such as Roche Holding AG's Tamiflu and GlaxoSmithKline's Relenza, and accelerate pharmaceutical industry efforts to create a vaccine to fight the swine flu strain, they said.
Monday evening, Chan convened a meeting of the WHO's emergency committee to assess the pandemic alert level which had previously been at 3 on the six-stage scale.
That panel recommended an increase to 4, which formally indicated that the infection could spread between humans to cause community-level outbreaks.
Earlier Wednesday, WHO acting assistant director-general Keiji Fukuda told journalists on a teleconference that swine flu had been shown to infect people who had not been to Mexico, and the outbreak showed no signs of slowing.