Vaccines for preventing typhoid fever

Anwar, Elspeth; Goldberg, Elad; Fraser, Abigail; Acosta, Camilo J.; Leibovici, Leonard

doi:10.1002/14651858.cd001261.pub3

Cited by 104 publications

(80 citation statements)

References 66 publications

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“…For typhoid patients with IP the case fatality rate considered was 17-22% across all age-groups, according to a recent review of the evidence [21]. Average vaccine effectiveness over the duration of immunity of the vaccine (3 years) was considered to vary between 30% and 70% [22].…”

Section: Epidemiological Parametersmentioning

confidence: 99%

Economic evaluation of typhoid vaccination in a prolonged typhoid outbreak setting: The case of Kasese district in Uganda

Carias

Wefula²,

Date

et al. 2015

Vaccine

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a b s t r a c tBackground: Vaccination has been increasingly promoted to help control epidemic and endemic typhoid fever in high-incidence areas. Despite growing recognition that typhoid incidence in some areas of subSaharan Africa is similar to high-incidence areas of Asia, no large-scale typhoid vaccination campaigns have been conducted there. We performed an economic evaluation of a hypothetical one-time, fixed-post typhoid vaccination campaign in Kasese, a rural district in Uganda where a large, multi-year outbreak of typhoid fever has been reported. Methods: We used medical cost and epidemiological data retrieved on-site and campaign costs from previous fixed-post vaccination campaigns in Kasese to account for costs from a public sector health care delivery perspective. We calculated program costs and averted disability-adjusted life years (DALYs) and medical costs as a result of vaccination, to calculate the cost of the intervention per DALY and case averted. Results: Over the 3 years of projected vaccine efficacy, a one-time vaccination campaign was estimated to avert 1768 (90%CI: 684-4431) typhoid fever cases per year and a total of 3868 (90%CI: 1353-9807) DALYs over the duration of the immunity conferred by the vaccine. The cost of the intervention per DALY averted was US$ 484 (90%CI: 18-1292) and per case averted US$ 341 (90%CI: 13-883). Conclusion: We estimated the vaccination campaign in this setting to be highly cost-effective, according to WHO's cost-effective guidelines. Results may be applicable to other African settings with similar high disease incidence estimates.

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Section: Epidemiological Parametersmentioning

confidence: 99%

Economic evaluation of typhoid vaccination in a prolonged typhoid outbreak setting: The case of Kasese district in Uganda

Carias

Wefula²,

Date

et al. 2015

Vaccine

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“…Two types of vaccines are available -live attenuated vaccine that is administered orally and contains live S.typhi and Vi capsular polysaccharide vaccine, that contains surface extracts of S. typhi bacteria and is administered intramuscularly. 8 Vi polysaccharide typhoid vaccines, because of their poor immunogenic and T cell independent properties, cannot be used in children less than two years of age. 9,10 These limitations were overcome by conjugating the Vi capsular polysaccharide vaccines to tetanus toxoid (Vi-TT).…”

Section: Introductionmentioning

confidence: 99%

Efficacy and safety of vi-tetanus toxoid conjugated typhoid vaccine (PedaTyph™) in Indian children: School based cluster randomized study

Mitra

Shah²,

Ghosh

et al. 2016

Human Vaccines & Immunotherapeutics

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Vi polysaccharide typhoid vaccines cannot be used in children <2 years owing to poor immunogenic and T cell independent properties. Conjugate vaccine prepared by binding Vi to tetanus toxoids (Vi-TT) induces protective levels even in children <2 years. We evaluated efficacy and safety following vaccination with a Vi-TT vaccine in children 6 months to 12 years of age. Overall, 1765 subjects were recruited from two registered municipal urban slums of southern Kolkata. Most of the children of the slum dwellers attended the schools in the locality which was selected with permission from the school authority. Schools were randomly divided into vaccinated (Test group) and unvaccinated group (Control group). Children and their siblings of test group received 2-doses of PedaTyph TM vaccine at 6 weeks interval. Control group received vaccines as per national guidelines. Adverse events (AEs) were examined after 30 minutes, 1 month and clinical events were observed till 12 months post-vaccination. Incidence of culture positive typhoid fever in the control group was 1.27% vis-a-vis none in vaccine group during 12 months. In subgroup evaluated for immunogenicity, an antibody titer value of 1.8 EU/ml (95% CI: 1.5 EU/ml, 2.2 EU/ml), 32 EU/ml (95% CI: 27.0 EU/ml, 39.0 EU/ml) and 14 EU/ml (95% CI: 12.0 EU/ml, 17.0 EU/ml) at baseline, 6 weeks and 12 months, respectively was observed. Sero-conversion among the sub-group was 100% after 6 weeks of post-vaccination and 83% after 12 months considering 4-fold rise from baseline. The efficacy of vaccine was 100 % (95% CI: 97.6%, 100%) in the first year of follow-up with minimal AEs post vaccination. Vi conjugate typhoid vaccine conferred 100% protection against typhoid fever in 1765 children 6 months to 12 years of age with high immunogenicity in a subgroup from the vaccine arm.

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“…Limited efficacy of OPV has contributed to the persistence of poliovirus transmission in several countries, delaying global eradication. Ty21a offers moderate efficacy against typhoid fever (reported at 48% over 3 years in a recent systematic review [13]), although there is no evidence to suggest that this is lower than protection offered to travelers from high-income, non-endemic countries [14,15]. One live-attenuated Shigella vaccine candidate was reactogenic and immunogenic when administered to North-American adults; however, when the same vaccine was tested in Bangladesh, it elicited no adverse reactions and failed to induce a serological response in any recipient [16,17].…”

mentioning

confidence: 99%

Causes of Impaired Oral Vaccine Efficacy in Developing Countries

et al. 2017

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Oral vaccines are less immunogenic when given to infants in low-income compared with high-income countries, limiting their potential public health impact. Here, we review factors that might contribute to this phenomenon, including transplacental antibodies, breastfeeding, histo blood group antigens, enteric pathogens, malnutrition, microbiota dysbiosis and environmental enteropathy. We highlight several clear risk factors for vaccine failure, such as the inhibitory effect of enteroviruses on oral poliovirus vaccine. We also highlight the ambiguous and at times contradictory nature of the available evidence, which undoubtedly reflects the complex and interconnected nature of the factors involved. Mechanisms responsible for diminished immunogenicity may be specific to each oral vaccine. Interventions aiming to improve vaccine performance may need to reflect the diversity of these mechanisms. Enteric pathogens are a substantial threat to public health. This threat takes many forms, from the toxin-producing bacteria (e.g., Vibrio cholerae) and flagellated protozoa (e.g., Giardia lamblia) that colonize the mucosal surface of the small intestine to the enteroviruses that are capable of spreading via the bloodstream to the CNS, causing acute flaccid paralysis (e.g., poliovirus). Each year, enteric pathogens cause hundreds of millions of cases of diarrhea and approximately 800,000 deaths, the vast majority of which occur among children in low-income countries [1]. The most common causes of childhood diarrheal morbidity include rotavirus, Cryptosporidium, enterotoxigenic Escherichia coli and Shigella [2].Vaccines against enteric pathogens are important tools for mitigating this disease burden. Oral vaccines offer several distinct benefits compared with parenteral vaccines. They can be produced in large quantities at relatively low cost, are easy to administer and have the capacity to induce local immunity in the intestinal mucosa, thereby protecting vaccinated individuals against subsequent infection and -by blocking onward transmission -enhancing herd immunity [3,4]. Currently licensed oral vaccines include live-attenuated poliovirus vaccines containing one, two or three serotypes, live-attenuated rotavirus vaccines (Rotarix R , RotaTeq R , Lanzhou lamb rotavirus vaccine [China only] and Rotavac R [India only]), live-attenuated cholera vaccine (CVD 103-HgR or Vaxchora TM ), inactivated cholera vaccines (Dukoral R and Shanchol R ) and live-attenuated typhoid vaccine (Ty21a). Other oral vaccines are in development, including those against Shigella, enterotoxigenic E. coli, Campylobacter and Clostridium difficile, as well as several novel rotavirus vaccine candidates (including the human neonatal vaccine RV3-BB [5] and an oral bovine pentavalent vaccine [6]).Yet oral vaccines have an Achilles' heel -their immunogenicity and efficacy is impaired in low-income countries that experience the greatest burden of enteric disease (Box 1). For example, Rotarix has a 1-year protective efficacy against severe rotavirus-associated gas...

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Vaccines for preventing typhoid fever

Cited by 104 publications

References 66 publications

Economic evaluation of typhoid vaccination in a prolonged typhoid outbreak setting: The case of Kasese district in Uganda

Economic evaluation of typhoid vaccination in a prolonged typhoid outbreak setting: The case of Kasese district in Uganda

Efficacy and safety of vi-tetanus toxoid conjugated typhoid vaccine (PedaTyph™) in Indian children: School based cluster randomized study

Causes of Impaired Oral Vaccine Efficacy in Developing Countries

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