On Wednesday, Merck & Co, voluntarily recalled 1.2 million units of their children’s vaccine for Haemophilus influenzae type b (Hib). The vaccine is used to protect children, under the age of 5, from bacterial meningitis.

The 11 lots of PedvaxHIB vaccine and two lots of its Comvax vaccine were reportedly recalled due to concerns over the sterility of the product. All but one of the 13 lots recalled were distributed in the US. Merck has said that the possibility for contamination for any individual vaccine is low and that all of the sterility testing performed on the recalled lots has not shown any contamination. All of the products involved in the recall were manufactured in West Point, Pennsylvania, and distributed starting in April 2007.

One question that should be asked is how is it possible for 13 lots of vaccine to be released without assurance they had been sterilized? Merck should be commended for taking the situation seriously and issuing a voluntary recall but a quality system assessment really needs to be performed to find out the root cause of this oversight. What assurance can Merck provide that a systematic failure such as this won’t happen again in the future? Luckily, the oversight has not caused any significant problems to date, but parents should be fully informed of which vaccines their child is being inoculated with and monitor any reaction at the site of inoculation and with the child’s general temperament.