On Dec. 12, 2007, Merck voluntarily recalled 1.2 million doses of Haemophilus influenzae type b (Hib) vaccines due to concerns about potential contamination with bacteria called B. cereus. The recall was a precaution, and after careful review, no evidence of B. cereus infection was found in recipients of recalled Hib vaccines.

In 2010, the Centers for Disease Control and Prevention (CDC) published a report summarizing the findings of a safety assessment after the 2007 Hib vaccine recall. The report was a collaborative effort involving the Food and Drug Administration (FDA) and CDC vaccine and laboratory experts.

The report found no evidence of B. cereus infection in people who received recalled Hib vaccines. Routine testing identified B. cereus in the vaccine manufacturing process equipment, but not in individual vaccine lots.  There were 5 reports of death. Tissue specimens were obtained for 4 of the 5 deaths; none of these specimens revealed evidence of B. cereus infection.