Under siege

Hospitals from Los Angeles, to London and Moscow are apparently besieged by flu. But Alan Hay of the WHO influenza collaborating centre at the National Institute for Medical Research in London, says the incidence of infection isn’t much higher than last year. The disruption is probably due to the greater virulence of this year’s prominent Sydney strain (sub-type H3N2). Elderly people are the worst affected and they are more likely to need hospital treatment.