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.
Click here to read the article, published in Clinical Infectious Diseases.