The committee said it was rejecting the vaccine because kidney cells from dogs are used to make it. The CSM said that using materials of animal origin in humans might present a risk from unknown infections.

"There are no other vaccines in the Department of Health's vaccination program which use this method of manufacture," reads a CSM press release. "As a result, there are a number of additional questions not all of which have been satisfactorily answered."

Miroslav Reinhardt, export director for Pavivac-maker Sevapharma, said the vaccine was safe and that his company has been cooperative with UK officials. He said the kidney cells were taken from dogs bred at farms that follow laws regulating such practices.

"We cooperated with the Medicines Control Agency (MCA) intensely -- we provided them with our documentation," he said, "and we hope they will reconsider their decision."

The vaccine was not licensed for distribution in the United Kingdom. If a medicine meets the special needs of individual patients, doctors in the United Kingdom are allowed to obtain unlicensed drugs.

First, however, the drug must be approved by the MCA, the executive agency of the Department of Health that ensures that all drugs meet the appropriate standards of safety, quality and efficacy.

From June to November, more than 5,000 doses of Pavivac were sent to the United Kingdom. Physicians directly requested the vaccine from Sevapharma.

Pavivac first came under fire in the United Kingdom in November, when the CSM suspended importation of the vaccine.
 

At the time, some British doctors criticized the action, calling the suspension "appalling scaremongering."

When the vaccine was suspended, Czech health officials said they tried to comply with the British government's demands for more information about Pavivac.

"Nothing [about the demands] was very specific or indicated that the product was substandard," said Milan Smid, a doctor for the Czech Regulatory Authority, the government agency that regulates drugs.

The agency reviewed the product, Smid said, and did not find any reason to discontinue or halt production in this country.

"We didn't have any indicator to take action against the product here," he said.

Reinhardt said that no one who has taken the vaccine, which has been used for 14 years, has experienced any serious adverse reactions. "More than 1.4 million children have been vaccinated with no problem," he said of the single mumps jab used in the Czech Republic.

Smid agreed.

"Through the years of use, we had a normal spectrum of the side effects that is comparable to other vaccines," he said. "There is no reason to take actions against this vaccine."

United Kingdom health officials said they were unsure how many of those doses imported into their country were administered to children.

The CSM has asked clinics to provide a record of children who received the jab so that any adverse reactions can be quickly and thoroughly investigated.

Breckenridge said that Sevapharma provided adequate information that proved Pavivac is effective in protecting children against mumps, as long as the child receives a second mumps vaccine between six to 10 months after the initial shot.

Currently, Pavivac is sold only in the Czech Republic and is not licensed in any European Union country. The company also manufactures a single measles vaccine, Movivac. British health officials are investigating its safety, even though the measles vaccine has not been imported into the United Kingdom.