GENEVA - The World Health Organization has ruled out swine flu vaccine as a reason for the deaths of 41 people who had taken the flu shot.

WHO vaccines chief Marie-Paule Kieny says investigations into several more deaths are ongoing.

WHO spokeswoman Nyka Alexander says the national authorities examined the 41 deaths in six countries.

Kieny said Thursday that vaccines against the pandemic H1N1 strain are as safe as vaccines against seasonal flu. She says only one out of 10,000 vaccinations results in an adverse reaction and of those only one in 20 are serious.

Millions of people have been vaccinated worldwide. As of last week at least 6,000 swine-flu related deaths were reported.