Vaccine-maker Sanofi Pasteur announced Tuesday a voluntary recall of 800,000 doses of a children's swine flu shot - about 10,000 of which have been distributed in Maryland - after tests showed the vaccine had lost some of its strength.

The recall is an issue of potency, not safety, and the federal Centers for Disease Control and Prevention and state health officials are urging parents not to worry if their child received a recalled shot. The vaccine still works against the virus since the reduction in strength was slight and not found to be "clinically significant," according to the CDC.


"This is a hiccup, but it's not a hiccup in terms of vaccine safety," said Frances Phillips, the state's deputy secretary for public health services. "Parents whose children got the one-time syringe don't need to call their pediatrician. There's no particular action that parents need to take in connection with this recall, which is a really good thing."

The vaccine, which comes in pre-filled syringes and is designed for children 6 months to 3 years old, requires two shots four weeks apart to be most effective. Parents should go ahead and have their children get a second shot, if they haven't already, the CDC said.


In Maryland, 10,300 doses of the recalled vaccine have gone out to 48 providers in 14 jurisdictions, most of them large pediatric practices, according to the state Department of Health and Mental Hygiene. Thirteen of those providers were in the Baltimore area. State officials would not give out a list of providers Tuesday.

This version of the vaccine is popular with doctors' offices because it's convenient and doesn't contain the mercury-based preservative thimerosal. The recalled doses make up just a fraction of that version of the vaccine - nearly 13 percent of the 79,900 pre-filled syringes for children distributed around the state. So far, Maryland has received 1.8 million doses of the swine flu vaccine.

The state health department sent e-mail messages to providers statewide alerting them of the recall, and specific alerts to doctors' offices that received affected batches of the vaccine.

"There are no safety concerns. There are no steps for parents to take, so we don't think it's necessary for pediatricians to comb through literally thousands of children's records to go through which ones were vaccinated and which ones were vaccinated with this particular lot," Phillips said.

Baltimore pediatrician Dr. Charles Shubin said his practice, Mercy Family Care, which has 16,000 patients, gave out 120 doses of the recalled vaccine. He doesn't plan to call parents of patients who received the dose, but expects to see them when they return for a booster shot.

"Our message is, make sure your child gets the second dose," he said. "We can't go back and change the one you got. But you can make sure they get the second dose."

He said the recall was frustrating for providers who have been clamoring since early fall for vaccine orders. Although the CDC placed children among the priority groups at the front of the line to be vaccinated, early shortages had providers struggling to keep up with demand.

Children are especially susceptible to the H1N1 virus, with disproportionate rates of illness, hospitalizations and death.


"When everyone was hyper about [the vaccine], we couldn't get it," Shubin said. "Now that everything has calmed down, we have more than we need."

The recall "doesn't bode well for people's confidence in the developing and distribution of a new vaccine," he said.

"But on the other hand, it's very common for vaccines to not demonstrate their good and bad until you get enough of it out there. When you start using it in large numbers, then you can see how it acts."