29 September 2018
An oral polio vaccine (OPV) manufactured by the company Bio-Med was found to be contaminated with the Type 2 poliovirus (vaccine strain). Type 2 poliovirus has been eradicated, and no outbreaks of this wild strain have been recorded since 1999. Consequently, modern live polio vaccines are typically bivalent, containing only two strains: Type 1 and Type 3.
The Indian vaccine manufacturer Bio-Med, based in Ghaziabad, produces polio vaccines for India’s government immunization programs. At this stage, an investigation is underway to track the problematic batches, and production at the plant has been halted. The reports do not specify the total number of children who were vaccinated with the contaminated batch. The incident came to light about two weeks ago after the virulent virus was isolated from a child who had received the vaccine. Subsequent testing confirmed that the vaccine was contaminated.
It is estimated that approximately 150,000 children received this "trivalent" vaccine. India, a nation of 1.3 billion people, was officially declared polio-free by the World Health Organization (WHO) in 2014.
Historical Context: The Cutter Incident
In 1955, shortly after the approval of the Inactivated Poliovirus Vaccine (IPV) developed by Jonas Salk, two batches of inactivated vaccines produced and marketed in the U.S. by Cutter Laboratories failed to undergo complete inactivation. These batches contained the live, virulent virus (Type 1). The incident ended tragically: 169 people were affected, including 56 vaccinated children and 113 family members who came into contact with those vaccinated. Ten people died.