The number of deaths in Mexico from swine influenza may be only “the tip of the iceberg” and, after a mild summer, the virus could return in a more virulent form, experts at the Stockholm based European Centre for Disease Prevention and Control said this week.

Angus Nicoll, the head of the centre’s influenza programme, said, “What we have now is a very mixed picture. We are not aware of how many people have a mild infection in Mexico and the few deaths could be the tip of the iceberg.”

Although …