Drug maker Novartis today trumpeted the effectiveness of a single dose of its anti-swine flu vaccine, boosting hopes that potentially tight supplies could go further when mass immunisation programmes start this month.
The outbreak of the H1N1 strain of flu, declared a pandemic on June 11th, has spread around the world and could eventually affect 2 billion people, according to World Health Organisation estimates.
Many experts expected that two doses per person would be needed by health authorities preparing for a possible second wave of infections at the start of the northern hemisphere winter.
Vaccination is expected to get under way in some countries this month with many others starting in October.
Novartis said its H1N1 vaccine had a strong immune response after just one dose in a pilot trial, and Chinese health authorities gave a green light to Sinovac, which says its vaccine also needs only one shot to be effective.
"First data is encouraging and indicates that should supply be limited due to low production yields, giving the population only one shot may be enough to provide protection from swine flu," Vontobel analyst Andrew Weiss said of the Novartis shot.
Another key variable is vaccine yield in the manufacturing process. Yields were initially low but the World Health Organisation said last month they were improving and one strain seemed to be yielding the same amount as seasonal vaccine.
Cell-based vaccines like Novartis's are quicker and easier to manufacture that traditional flu vaccines, which are grown in chicken eggs, but supplies are limited for now -- they currently make up about 30 per cent of the Swiss group's capacity.
Novartis said the trial with 100 volunteers run by Britain's Leicester University showed a potentially protective immune response in 80 per cent of subjects after one dose and more than 90 per cent after two doses. Other studies with more than 6,000 adults and children are continuing.
Sinovac, the first company to complete clinical trials, received approval from Chinese health authorities to mass produce a vaccine for the new strain of H1N1 and raised its annual sales forecast.
Reuters