Just one dose of vaccine is enough to immunize against the A/H1N1 swine flu virus, according to an advisory body to the World Health Organization, Marie-Paule Kieny, the WHO's Director of Initiative for Vaccine Research, said Friday.

European health regulator EMEA earlier this month recommended two shots of vaccine be given.

The Strategic Advisory Group of Experts, or SAGE, also concluded it is safe for pregnant women to receive licensed vaccines, Kieny said, including both adjuvanted and non-adjuvanted vaccines.

"There's no reason to distinguish between the adjuvanted and the non-adjuvanted vaccines, they have the same safety profile, according to SAGE," Kieny said.

Adjuvanted vaccines contain a booster ingredient that makes one shot more effective, but may also be the cause for rare, but severe, side effects.

It is possible to co-administer a seasonal and pandemic vaccine without safety concerns, according to SAGE. The only exception is if both vaccines are nasal sprays, Kieny said.

So far, EMEA has approved three pandemic vaccines - Novartis AG's (NVS) Focetria and GlaxoSmithKline PLC's (GSK) Pandemrix, which are both adjuvanted, and Baxter International Inc.'s (BAX) non-adjuvanted Celvapan.

The U.S., which so far used only non-adjuvanted vaccines, has ordered from Novartis, Sanofi-Aventis SA (SNY), CSL Ltd. (CSL.AU), GlaxoSmithKline PLC and MedImmune, a unit of AstraZeneca PLC (AZN).

WHO Web site: http://www.who.int

-By Julia Mengewein, Dow Jones Newswires, +41 43 443 80 45, julia.mengewein@dowjones.com