Lessons learned from a cluster of immunization errors in newborns.

Background: Vaccines are safe and effective, but adverse reactions can occur. Immunization errors (IEs) are one of the types of adverse events following immunization. The Moroccan Pharmacovigilance Centre (MPC) received a cluster of IEs from a maternity university hospital (MUH) regarding six newborns who were inadvertently administered rocuronium instead of hepatitis B (HepB) vaccine.