Swine flu may have peaked – but it could come back

A fundamental disagreement between Mexican health authorities and the World Health Organisation has emerged, with Mexico claiming the outbreak of swine fever virus has already peaked and the WHO saying it is too early to tell.

The Mexican health minister Jose Angel Cordova said on Sunday: "The evolution of the epidemic is now in its declining phase." But WHO spokesman Gregory Hartl said there was no proof from Mexico and, generally, health authorities must remain on alert.

Even if the current "round of activity" does turn out to have peaked, said Hartl, "There is a high possibility that this virus will come back, especially in colder periods." And when it does come back, it could be more serious.

This message was reiterated by UK Health Secretary Alan Johnson on Sunday. "Our evidence from all previous pandemics is you get two phases," he said. "So you get a first wave which is often very mild and then you get a much more serious wave that comes along in the autumn and the winter."

The good news is that this gives governments and drug companies the summer to prepare and make adequate supplies of a vaccine.

In the meantime, the WHO reports that 900 cases have now been confirmed across five continents. Person-to-person transmission has been confirmed in six countries, including Britain.

Beyond Mexico, still only one death has been confirmed, that of a 23-month-old Mexican baby across the border in Texas. The United States remains the most seriously affected country outside Mexico, with nearly 250 confirmed cases across 35 states, including more than 60 children at a New York school.

Dr Anne Schuchat of the US Centers for Disease Control and Prevention said: "Virtually all of the United States probably has this virus circulating now." She expects cases to become more severe and to lead to deaths. However, she stressed that every year 36,000 people die in the US after contracting seasonal flu.