Medical professionals maintain there was no strong evidence to support the theory that the vaccine caused the neurological disorder. And they said overblown safety concerns should not prevent people, particularly those at high risk of infection such as children and pregnant women, from receiving this year's swine flu vaccine.
"Public perception plays a very important role in how vaccination campaigns succeed," Treanor said. "It will be important to provide transparency and up-to-date safety information."
Donna Cary, a spokeswoman for Sanofi-Aventis, the company that will manufacture the swine flu vaccine, said that they have received an order from the Department of Health and Human Services for a bulk amount of vaccine but that the formula is still to be determined. However, they expect they will be manufacturing two varieties of the vaccine.
"The anticipation is that we will be producing both a thimerosal-free and a vaccine containing thimerosal," Cary said. "Because of the quantities they're talking about, multi-dose vials will be used."
Using thimerosal and multi-dose vials makes vaccines cheaper to manufacture and distribute, Treanor said.
Still, Pavia said, there will likely be enough doses of thimerosal-free vaccine for very young children whose parents fear that the chemical will have some negative effect. Taking such steps, he said, may further ensure than those who need this important vaccine will receive it.
ABC News' Lisa Stark contributed to this report.