Use of the typhoid conjugate vaccine in endemic settings

Multidrug-resistant and extensively drug-resistant (XDR) strains of Salmonella enterica serotype Typhi (S Typhi) are increasingly creating serious clinical economic challenges for patients with typhoid fever in south Asia.1Klemm EJ Shakoor S Page AJ et al.Emergence an serovar clone harboring a promiscuous plasmid encoding resistance to fluoroquinolones third-generation cephalosporins.mBio. 2018; 9: e00105-e00118Crossref PubMed Scopus (274) Google Scholar There is high disease burden fever, mostly among children urban slums, where safe water proper sanitation infrastructure lacking.2Brooks WA Hossain A Goswami D al.Bacteremic slum, Bangladesh.Emerg Infect Dis. 2005; 11: 326-329Crossref (174) Scholar, 3Luby SP Urban slums: supportive ecosystem typhoidal salmonellae.J 218: S250-S254Crossref (9) The provision these facilities requires large financial investments the political will eliminate spread infectious diseases. To prevent transmission, WHO has recommended introduction single-dose conjugate vaccine infants aged 6 months older.4World Health OrganizationTyphoid vaccines: position paper, March 2018 — recommendations.Vaccine. 2019; 37: 214-216Crossref (70) In Lancet Global Health, Mohammad Tahir Yousafzai colleagues5Yousafzai MT Karim Qureshi al.Effectiveness against culture-confirmed outbreak setting Hyderabad, Pakistan: cohort study.Lancet Glob Health. 2021; e1154-e1162Summary Full Text PDF (1) report effectiveness Vi-polysaccharide tetanus toxoid Typbar-TCV (Bharat Biotech International, India) XDR Pakistan. authors carried out vaccination campaign 10 years Qasimabad Latifabad subdistricts After vaccination, systemic surveillance was done between Feb 21, 2018, Dec 31, 2019, analyse 23 407 vaccinated unvaccinated years. Vaccine 55% (95% CI 52–57) suspected 95% (93–96) blood-culture-confirmed Typhi. also 97% 95–98) effective Typhi.5Yousafzai 2008, unconjugated live-attenuated Ty21a vaccines, licensed individuals older than 2 years, use endemic epidemic settings; however, increased incidence been reported or younger such settings.6Saha SK Baqui AH Hanif M al.Typhoid Bangladesh: implications policy.Pediatr Dis J. 2001; 20: 521-524Crossref (96) 7Ganesh R Karthik Prabhu Janakiraman L Typhoid below age.Ind J Pediatr. 2016; 83: 605-606Crossref (2) present study by colleagues, set Pakistan, provides evidence substantial efficacy all age groups, including as young months: 92–97) 6–59 months, further demonstrating timely settings.5Yousafzai Kolkata, India,8Mohan VK Varanasi V Singh al.Safety immunogenicity Vi polysaccharide-tetanus (Typbar-TCV) healthy infants, children, adults areas: multicenter, 2-cohort, open-label, double-blind, randomized controlled phase 3 study.Clin 2015; 61: 393-402Crossref (100) shown that highly immunogenic even 6–23 inducing long-lasting serum anti-Vi IgG antibodies participants groups. study,5Yousafzai blood collected from 1058 at 28–42 days, 1 measure age-stratified antibody response, but data have not reported. Publication dissemination would be beneficial, it important understand pattern induced immune responses their duration participants. Additionally, continuous analysis cohort, subsequent follow-up reports valuable examine protective this over time. It establish, instance, whether booster dose needed appropriate timing dose. Despite limitations, several strengths must acknowledged. This investigated large-scale, population-based Moreover, before colleagues,5Yousafzai no had explore months. single reducing transmission community during peak monsoon season curtailing major outbreak. Acceleration Consortium sponsored prospective studies Asia (Bangladesh Nepal) Africa (Malawi), which generate data, providing greater clarity about level herd immunity conferred vaccine.9Meiring JE Gibani (TyVAC): designs: accelerating vaccines global enteric fever. Report meeting held on 26–27 October 2016, Oxford, UK.Vaccine. 2017; 35: 5081-5088PubMed Preliminary randomised trial Nepal already 1-year 81·6% 58·8–91·8; p<0·001) 9 16 years.10Shakya Colin-Jones Theiss-Nyland K al.Phase Nepal.N Engl Med. 381: 2209-2218Crossref (66) Ongoing provide great value typhoid-fever-endemic regions, incorporation into routine immunisation programmes countries control antimicrobial globally. No funding required Comment article. icddr,b receives core support Government Bangladesh, Canada, Sweden, UK. All declare other competing interests. Effectiveness studyTypbar-TCV protecting infection setting, able, moderate deployment, curtail densely populated setting. shows irrespective resistance. Full-Text Open Access