The prospect of a boost to sales from swine flu vaccines and antivirals added excitement to solid second-quarter results from GlaxoSmithKline.

More than 700 people, including 31 in the UK, have died from the H1N1 virus, which the World Health Organisation says is spreading faster than any previous flu pandemic. Analysts expect it to boost not only GSK but Roche and Sanofi-Aventis.