Merck Misled on Vaccines, Some Say

In September 1999, amid rising concern about the risks of mercury in childhood vaccines, Merck announced that the Food and Drug Administration had approved a preservative-free version of its hepatitis B vaccine.

"Now, Merck's infant vaccine line," the company's press release said, "is free of all preservatives."

But Merck continued to distribute vaccine containing the chemical known as thimerosal, along with the new product, until October 2001, according to an FDA letter sent in response to a congressional inquiry.

The thimerosal-containing supplies had expiration dates in 2002.

Merck executives confirmed the details in the FDA letter but defended the accuracy of Merck's announcement in 1999, saying the company had indeed begun to produce preservative-free vaccine.

Merck continued to supply the preservative-containing version "during the transition period to ensure an adequate supply of vaccine to help protect the nation's children," said spokeswoman Mary Elizabeth Blake. She said package labels disclosed which lots of vaccine were preservative-free.

Parent groups and a congressional critic of U.S. vaccine policy are crying foul.

"As far as the world knew, the product coming out of Merck had no thimerosal in it," said Sallie Bernard, executive director of Safe Minds, a group concerned about childhood exposure to mercury, a neurotoxin. Parents and doctors who wanted a thimerosal-free product "would be totally confused," she said.

Rep. Dave Weldon, a Florida Republican and a physician, said what Merck did was "misleading."

"You had people literally into 2002 getting shots with mercury, having been told it was all taken out in 1999," he said. "There should have been a much more cautious announcement that we're going to eliminate the mercury over time." The FDA letter was sent to Weldon in June 2003 in response to his questions about progress in removing mercury from vaccines.

Thimerosal, which is nearly 50% ethyl mercury, has largely been eliminated from most routine childhood vaccines, though it still is present in most flu shots. It had been widely used as a sterilizing agent to prevent bacterial contamination from repeated insertion of needles into multi-dose vials of vaccine.