Margaret Chan, the WHO director-general, says swine flu "has got to be the biggest pandemic ever in terms of the number of countries and people affected".
Chan, who began leading the organisation in 2007, was the first WHO head in 41 years to announce (on 11 June) that a new virus had reached pandemic status.
While the 1918 pandemic remains the biggest killer, Chan says that she expects the swine flu pandemic to worsen and return in two or three waves: "I hope we don't see the 1918 picture. But we should expect to see more people infected, and more severe cases coming up, including deaths".
Information on the number of swine flu cases in Africa is misleading, Chan admits, as proper testing in the developing world has only been possible since May when the WHO began to distribute lab kits. The developing world will also have limited access to drugs such as Tamiflu.
"Is it fair for these countries to go into a pandemic empty-handed?" Chan asks.
Chan has demanded that drug companies offer free doses of antivirals — Roche has provided 5.6 million doses. Vaccines present a bigger challenge because of limited production capacity. Chan is trying to persuade manufacturers to free up ten per cent of their capacity for developing countries.
While a vaccine could be available as early as August, "having a vaccine available is not the same as having a vaccine that is proven safe", says Chan. "Clinical trial data will not be available for another two to three months."