GENEVA (Reuters) - The H1N1 pandemic is over and the global outbreak turned out to be much less severe than was feared just over a year ago, the head of the World Health Organization (WHO) said on Tuesday.
WHO director-general Margaret Chan once again rebutted criticism that the United Nations agency had hyped the first pandemic in more than 40 years, whose mildness left some Western governments holding huge stockpiles of unused vaccines.
The Hong Kong public health expert said the world had been lucky the H1N1 virus had not mutated into a more deadly form and that a safe vaccine developed in record time remained effective against it.
“We are now moving into the post-pandemic period. The new H1N1 virus has largely run its course,” Chan said.
“That was the right call,” she said, defending the decision taken in June last year to declare a pandemic.
The swine flu virus will continue to circulate as part of seasonal influenza for years to come, requiring health authorities to remain vigilant, she told a news conference.
It still threatens high-risk groups including pregnant women who would benefit from vaccination, she said.
Stockpiled H1N1 vaccines remain effective against the strain and so far the virus has not developed widespread resistance to the antiviral oseltamivir, the best treatment, she said.
The WHO’s downgrading of the H1N1 outbreak to “post-pandemic” was based on recommendations by external influenza experts who conducted a review earlier in the day.
“I think even if we see severe outbreaks occurring in some countries — which is still definitely possible — that the global threat is really much lower and much different than a year ago,” Keiji Fukuda, WHO’s top flu expert, told reporters.
In June 2009, the WHO said a new swine flu virus, H1N1, that emerged in the United States and Mexico and spread around the world in six weeks, was the first pandemic since 1968. A full pandemic corresponds to phase 6 on the WHO’s six-point scale.
“We need to continue to maintain our vigilance and not be complacent,” Chan said, noting that outbreaks continued in countries including India and New Zealand.
The behavior of influenza viruses is notoriously difficult to predict and no two pandemics are alike, flu experts say.
“I am very pleased that European member states prepared for something worse. I’d rather have it go that way than their planning for less or not being prepared at all,” Angus Nicoll, influenza program coordinator at the European Center for Disease Prevention and Control, told Reuters Tuesday.
The WHO has also rejected allegations that it acted under the influence of drug companies in declaring a pandemic.
Chan said that three viruses were now circulating as part of a “mixed virus pattern” in many countries, typically seen during seasonal epidemics. These were H1N1 and H3N2 — both type ‘A’ influenza — as well as type ‘B’.
Either H1N1 vaccine or a trivalent (triple shot) vaccine against the three strains should be used to inoculate those at risk, depending on their availability, she said.
“Pandemic and seasonal vaccine in both hemispheres confer the same protection (against H1N1),” Fukuda said.
An estimated 350 million people worldwide have been vaccinated against H1N1, he said.
Dozens of companies make influenza vaccines, including Sanofi-Aventis, GlaxoSmithKline, Novartis, AstraZeneca and CSL. Roche makes the frontline antiviral oseltamivir, marketed as Tamiflu.
The U.S. Centers for Disease Control and Prevention said the WHO pronouncement will not alter U.S. plans for the upcoming flu season. The CDC recommends that everyone over 6 months of age be vaccinated against seasonal flu this year, the most universal recommendation yet for flu vaccines.
The CDC said vaccine manufacturers are predicting an ample supply of U.S. flu vaccine, which will protect against the 2009 H1N1 swine flu virus, plus the most common strains of the H3N2 and the influenza B virus.
The CDC last month said manufacturers have forecast they will have 170 million doses of flu vaccine for the 2010-2011 U.S. flu season.
Some 18,450 people worldwide are confirmed to have died from H1N1 infections, including many pregnant women and young people. But WHO says that it will take at least a year after the pandemic ends to determine the true death toll, which is likely to be much higher.
Seasonal flu kills an estimated 500,000 people a year, 90 percent of them frail elderly people, according to the WHO. The 1957 and 1968 pandemics killed about 2 million and 1 million people, respectively, it says.
Additional reporting by Laura MacInnis and Julie Steenhuysen; Editing by Louise Ireland and Cynthia Osterman.