Evaluation of Vaccine Safety After the First Public Sector Introduction of Typhoid Conjugate Vaccine-Navi Mumbai, India, 2018.

Background In December 2017, the World Health Organization (WHO) prequalified the first typhoid conjugate vaccine (TCV) (Typbar-TCV). While no safety concerns were identified in pre- and post-licensure studies, WHO's Global Advisory Committee on Vaccine Safety recommended robust safety evaluation with large-scale TCV introductions. During July-August 2018, the Navi Mumbai Municipal Corporation (NMMC) launched the world's first public sector TCV introduction. Per administrative reports, 113,420 children 9 months-14 years old received TCV. Methods We evaluated adverse events following immunization (AEFI) using passive and active surveillance via 1) reports from the passive NMMC AEFI surveillance system, 2) telephone interviews with 5% of caregivers of vaccine recipients 48 hours and 7 days post-vaccination, and 3) chart abstraction for adverse events of special interest (AESI) among patients admitted to 5 hospitals using the Brighton Collaboration criteria followed by ascertainment of vaccination status. Results We identified 222/113,420 (0.2%) AEFI through the NMMC AEFI surveillance system: 211 (0.19%) minor, 2 (0.002%) severe, and 9 (0.008%) serious. At 48 hours post-vaccination, 1,852/5,605 (33%) caregivers reported one or more AEFI, including injection site pain (n=1,452, 26%), swelling (n=419, 7.5%), and fever (n=416, 7.4%). Of the 4,728 interviews completed at 7 days post-vaccination, the most reported AEFI included fever (n=200, 4%), pain (n=52, 1%), and headache (n=42, 1%). Among 525 hospitalized children diagnosed with an AESI, 60 were vaccinated; no AESI were causally associated with TCV. Conclusions No unexpected safety signals were identified with TCV introduction. This provides further reassurance for the large-scale use of Typbar-TCV among children 9 months-14 years old.