Quality of Vaccines Related Adverse Event Following Immunization Between 2008 and 2017

Abstract

The cause of adverse events following immunization may come from various factors. Vaccine quality testing is a part of a causality assessment in serious cases. The objective of this study was to collect and analyze the vaccine quality which was tested by Institute of Biological Products, Department of Medical Sciences, between 2008 and 2017 for relevant agencies’ information. There were a total of 81 vaccine samples tested comprising of DTPw-HB (32), OPV (16), Influenza (8), DTPw, dT and HB (5 each), MMR (3), JE inactivated and IPV (2 each), BCG, Rabies and DTPa-HB-IPV+Hib (1 each). The results showed that vaccines had met the acceptance criteria for identity, potency, safety and physico-chemical testing of each product except the appearance of particles in tests of DTPw-HB (4 samples) and JE (1 sample), lower amount of thimerosal in DTPw-HB (1 sample) while the sterility test of each one opened vial of DTPw-HB and OPV had found B.cerus and A. acidoterrestris contamination respectively. The particles found in DTPw-HB might have been caused from storing vaccines outside the range of 2-8 oC while the particles in JE vaccine were endogenous compounds. Testing to confirm virus strains by RT-PCR and sequencing which were beyond the MMR specification had identified changes to nucleotide 1 position of mumps virus but there was no effect to amino acid sequence. In conclusion, most results of adverse event related vaccines between 2008 and 2017 passed their product specifications. The results complied with the previous report of adverse event related vaccines between 2003 and 2007 which were found not to have failed because of substandard production. Therefore, repeat testing in case of adverse event may not be necessary if those vaccines have been released by lot release system. Exception may appy if there is any strong evidence related to vaccine quality.