After two infants died and 29 others fell ill after being vaccinated against hepatitis B in the southern state of Chiapas on Friday, the Instituto Mexicano del Seguro Social (Mexican Social Security Institute—IMSS) announced yesterday that it has sent samples of the vaccines to Mexico City for analysis. The move follows the launch of an investigation into the case by the Comisión Nacional de Derechos Humanos (CNDH) on Saturday, and a visit to the affected families by the IMSS director, José Antonio González, and the governor of Chiapas, Manuel Velasco, on Sunday.
On Saturday, the IMSS announced the national suspension of tuberculosis, rotavirus, and hepatitis B vaccinations, but later clarified that the suspension applied only to the lots of hepatitis B vaccine used in the municipality of Simojovel, where the affected children were vaccinated. “We still don’t know what caused the problem,” said Rodrigo Romero Feregrino, secretary of the Asociación Mexicana de Vacunología (Mexican Vaccinology Association). “We must wait for the results of the investigation. I think it was a human error.”
According to the Mexican daily La Jornada, the principal theory among specialists and the Mexican Secretaría de Salud (Health Secretariat—Ssa) is that the deaths and sickness were caused by errors in the storage or handling of the vaccines. According to Rafael Gual Cosío, the director general of the Cámara Nacional de la Industria Farmacéutica (National Pharmaceutical Industry Chamber—Canifarma), the vaccines may have been spoiled due a lapse in temperature control during storage or transport. In an interview with the news site El Economista, he said, “What surely happened here is that part of the vaccine that was sent to this locality didn’t maintain adequate cold chains, at some point it was broken, and that’s what could have caused the vaccines to decompose.”
Meanwhile, the parents of the children in Chiapas await answers. “They ask for justice,” Marcelo Pérez, a priest in Simojovel municipality said. “They want a deep investigation into what really happened, and why. That’s what they ask for. There’s a lot of pain.”