More than a million doses of a common vaccine given to babies as young as two months was being recalled in the United States on Wednesday because of contamination risks, but the Canadian market is not affected.

The recall is for 1.2 million doses of the vaccine for Hib, which protects against meningitis, pneumonia and other serious infections, and a combination vaccine for Hib and hepatitis B. The vaccine is recommended for all children under five and is usually given in a three-shot series, starting at two months.

Drug maker Merck & Co. announced the recall Wednesday after testing showed a sterilization problem in a Pennsylvania factory.

"The potential for contamination of any individual vaccine is low," said Merck spokeswoman Kelly Dougherty.

Dr. Julie Gerberding, head of the Centers for Disease Control and Prevention, echoed that in a news conference.

"This is not a health threat in the short run, but it is an inconvenience," she said.

Alain Desroches, a spokesman for the Public Health Agency of Canada, said the vaccine is approved for use in Canada.

"But (it) has not been actively marketed by the company in Canada and is not used by any province and territory in publicly funded immunization programs," he said in an e-mail.

"Those products are not distributed in Canada, so this is a U.S.-only recall," said Merck Frosst Canada spokesman Vincent Lamoureux.

"There is no link to our business in Canada."

On Tuesday, Health Canada advised provinces and territories not to use another Merck Frosst product - three lots of measles, mumps and rubella vaccine - while they investigate five suspected cases of anaphylaxis in Alberta patients. All the patients were young adults who had a previous history of allergy.

The five cases were associated with lot 1529U of MMR-II vaccine.

Altogether, 276,290 doses that were distributed in Canada are subject to the quarantine, according to Elise Giasson, another Merck Frosst spokeswoman.

They had been distributed to all provinces except Saskatchewan, she said.

Sheila Murphy, manager of public affairs, said a letter has been sent to customers who bought the vaccine and may have received one of the three lots. Alberta bought most of it, she noted.

"In most of the other provinces, it hasn't been used yet, or very little of it has been," she said.