New Delhi, Sept. 3: Early results from the world’s first trial of a vaccine against the pandemic H1N1 flu have shown a strong immune response after just one dose, British researchers announced today.

The trial, conducted by researchers at the University of Leicester, was aimed at evaluating the vaccine’s safety and its capacity to generate an immune response among healthy volunteers between 18 and 50.

The vaccine, developed by Novartis, produced a potentially protective immune response in 80 per cent of the volunteers who received one dose, and in more than 90 per cent of volunteers who received two doses. The vaccine was well tolerated and pain at the injection site was the most frequent side effect, Novartis said today.

Indian health officials said the company had offered to help the government test the vaccine on volunteers in India.