In preparation for swine-flu vaccinations next month, the state of Washington's Health Department has temporarily suspended a rule that limits the amount of a mercury preservative in vaccines given to pregnant women and children under the age of 3.

Thimerosal has been eliminated from most vaccines in the United States, and the compound may  be linked to autism. But it will be added to the bulk of swine-flu vaccines.

Thimerosal will be added to the vaccine because it is being produced in vials that contain enough medication for 10 shots. The mercury compound kills bacteria, lowering the risk that the drug will be contaminated by needles used to withdraw separate doses.

A smaller amount of mercury-free vaccine will be produced in single-dose vials. Nasal sprays do not contain mercury but are not recommended for children under the age of 2 and pregnant women, because they contain live, weakened virus.