GENEVA, April 27 (Reuters) - A World Health Organisation emergency committee could raise its pandemic alert level to phase 4 or 5 as a deadly swine flu outbreak shows no signs of slowing, a spokesman for the agency said on Monday.
Going to phase 4 would mean the WHO believes that a potential pandemic virus has shown it could transmit from person to person and cause large outbreaks.
WHO spokesman Gregory Hartl also told a telephone briefing that U.S. health officials have taken the first steps toward producing a vaccine against the virus that has killed more than 100 people in Mexico and spread to North America and Europe. (Reporting by Jonathan Lynn and Robert Evans; Writing by Michael Kahn; Editing by Charles Dick)