Only one dose of vaccine is needed for protection against pandemic H1N1 flu and the jabs have so far proved to be safe, the World Health Organisation said on Friday, citing immunisation experts.

Health experts have been debating whether one or two shots are necessary to protect against H1N1, known as swine flu. The number of doses required is key to estimating how many vaccines are needed in total.

The U.N. health agency has repeatedly sought to reassure people around the world that the H1N1 vaccines being made by 25 different companies - with various formulations - are all safe.

Earlier this week, its Strategic Advisory Group of Experts on Immunisation (SAGE) examined vaccines for H1N1, which tends to affect teenagers and young adults most.

“The experts reviewed early results from the monitoring of people who have received pandemic vaccines and found no indication of unusual adverse reactions,” the Geneva-based WHO said in a statement.

“Some adverse events following vaccination have been notified, but these are well within the range of those seen with seasonal vaccines, which have an excellent safety profile.”

The experts said health officials should continue to monitor H1N1 vaccine programmes for adverse events - the technical term for severe complications such as illness or death.

The SAGE committee recommended that a single dose of H1N1 vaccine should be used for adults and adolescents from age 10.

It said more studies were needed on the effectiveness of vaccines in children aged up to 10 years. Where national health authorities have made children a priority for vaccination, they should aim to vaccinate as many children as possible with a single dose, the group concluded.

The recommendation corresponds to WHO’s estimate earlier this month that one dose suffices. Last week Europe’s drug watchdog said two doses would be preferable.

In its statement, the WHO said 1 to 10 percent of patients who developed a serious illness needed hospital treatment. Of those, 10 to 25 percent needed treatment in an intensive care unit and 2 to 9 percent died.

Very young children are most likely to require hospital treatment for the H1N1 virus.

In most cases, the WHO said is safe to administer vaccines for H1N1 and regular seasonal flu together.
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By Jonathan Lynn

GENEVA (Reuters)