THE Health Ministry is recommending that pregnant women should be given only one of the two versions of the Influenza A (H1N1) vaccine available here.

The ministry told The Straits Times yesterday that expectant mothers should be given vaccines which do not contain an adjuvant, or chemical additive.

There are two types of H1N1 vaccines available here: Australian pharmaceutical giant CSL's Panvax, which does not contain the additive, and British company GlaxoSmithKline's (GSK) Pandemrix, which does.

The additive in Pandemrix acts as an immunity booster, allowing the immune system to react faster to the vaccine. The additive also allows the vaccine to be given in smaller doses.

Countries like Switzerland had recently restricted the use of Pandemrix for pregnant women, because of the lack of data on its side-effects for this group.

The World Health Organisation had also recommended that pregnant women should receive an additive-free version of the vaccine.

Yesterday, the Health Ministry told The Straits Times that vaccines without additives have a longer track record of safety when it comes to pregnant women.

It is thus recommending that such vaccines be used if available.

The ministry is also recommending that only women in their last six months of pregnancy be given the H1N1 shots.

However, because pregnant women are at higher risk of being severely affected by the virus, they should not refrain from getting the shots altogether.

Right now, the ministry recommends that people at high risk - pregnant women, those with medical conditions like heart disease and those travelling to countries in the Northern Hemisphere, where winter increases the risk of catching the pandemic flu - should get the H1N1 vaccine.

Meanwhile, demand for the vaccine has outstripped supply. Currently, 271,180 doses have been ordered, but only 250,000 doses are available.

However, 106,400 doses from CSL are expected to arrive at the weekend.

This article was first published in The Straits Times.