Typhoid vaccination: the Asian experience

DeRoeck, Denise; Ochiai, R. Leon; Yang, Jing; Anh, Đặng Đức; Alag, Vibha; Clemens, John D.

doi:10.1586/14760584.7.5.547

Cited by 41 publications

(39 citation statements)

References 19 publications

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“…Typhoid is generally believed to be a disease of older children but studies have indicated that typhoid causes significant morbidity and mortality in children below five years of age [3][4][5]. Vaccination is recommended as a key intervention in the control of typhoid fever [6] especially given the emergence of multidrug resistant strains of S. Typhi [7,8].…”

Section: Introductionmentioning

confidence: 99%

A Study on Longevity of Immune Response after Vaccination with Salmonella Typhi Vi Conjugate Vaccine (Pedatyph™) in Children

Chinnasami

Sadasivam

Aravindhan

et al. 2015

JCDR

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Section: Introductionmentioning

confidence: 99%

A Study on Longevity of Immune Response after Vaccination with Salmonella Typhi Vi Conjugate Vaccine (Pedatyph™) in Children

Chinnasami

Sadasivam

Aravindhan

et al. 2015

JCDR

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“…Vi-DT was stable under repeated freeze-thaw (20 cycles). We plan to perform clinical evaluation of the safety and immunogenicity of Vi-DT when added to the infant combination vaccines.Typhoid fever, a serious systemic infection caused by Salmonella enterica serovar Typhi, remains a major public health problem in Central Asia, Southeast Asia, Africa, and Latin America (11,52,53). It was estimated that more than 21 million cases of typhoid fever and Ͼ200,000 deaths occurred in 2000 (10).…”

mentioning

confidence: 99%

Physical and Chemical Characterization and Immunologic Properties ofSalmonella entericaSerovar Typhi Capsular Polysaccharide-Diphtheria Toxoid Conjugates

Cui

Carbis

et al. 2010

Clin Vaccine Immunol

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Typhoid fever remains a serious public health problem in developing countries, especially among young children. Recent studies showed more than 50% of typhoid cases are in children under 5 years old. Licensed vaccines, such as Salmonella enterica serovar Typhi capsular Vi, did not confer protection against typhoid fever for this age group. Vi conjugate, prepared by binding Vi to Pseudomonas aeruginosa recombinant exoprotein A (rEPA), induces protective levels of antibody at as young as 2 years old. Because of the lack of regulatory precedent for rEPA in licensing vaccines, we employed diphtheria toxoid (DT) as the carrier protein to accommodate accessibility in developing countries. Five lots of Vi-DT conjugates were prepared using adipic acid dihydrazide (ADH) as the linker. All 5 lots showed consistency in their physical and chemical characteristics and final yields. These Vi-DT conjugates elicited levels of IgG anti-Vi in young mice significantly higher than those in mice injected with Vi alone and induced a booster response upon reinjection. This booster effect was absent if the Vi replaced one of the two conjugate injections. Vi-DT was stable under repeated freeze-thaw (20 cycles). We plan to perform clinical evaluation of the safety and immunogenicity of Vi-DT when added to the infant combination vaccines.Typhoid fever, a serious systemic infection caused by Salmonella enterica serovar Typhi, remains a major public health problem in Central Asia, Southeast Asia, Africa, and Latin America (11,52,53). It was estimated that more than 21 million cases of typhoid fever and Ͼ200,000 deaths occurred in 2000 (10). The treatment of patients and management of asymptomatic carriers are becoming more difficult due to the worldwide emergence of multidrug-resistant (MDR) strains (2,15,29,42,43). Vaccination is considered the most promising strategy for the control of typhoid fever in developing countries (11,19,52,53).Typhoid fever in children younger than 5 years old has often been unrecognized due to atypical clinical symptoms, difficulties in the number and volume of blood drawings, and use of less than optimal culture media (35,46). Several studies have shown that the incidence of typhoid fever among children less than 5 years old is similar to that in school age children and young adults (14,27,34,50,51).The 3 licensed typhoid vaccines have limited efficacy, and none are suitable for young children under 5 years old. The use of heat-inactivated whole-cell vaccine was suspended in many countries because of its reactogenicity. The parenteral Vi polysaccharide and the live attenuated oral Ty21a vaccine were introduced in the late 1980s; both vaccines are well accepted and confer moderate protection (50 to 70%) in older children and adults. However, neither vaccine is licensed for routine immunization of infants (52).The Vi capsular polysaccharide is both an essential virulence factor and a protective antigen for S. Typhi (36,38,39). The concentration of serum IgG anti-Vi is correlated with immunity to the pathogen (22...

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“…A similar outcome has been observed in China where targeting of high incidence areas resulted in decreased typhoid incidence. 11 In Cakaudrove subdivision (65% vaccinated), incidence decreased post-campaign, but the proportion of cultures positive for Typhi and the number of hospitalized cases was similar before and after the campaign. It is not possible for us to assess whether ongoing typhoid in Cakaudrove is occurring primarily within unvaccinated areas, or whether the local epidemiology or targeting strategy made the campaign less effective than in other subdivisions.…”

Section: Discussionmentioning

confidence: 93%

“…Recently, data have become available from typhoid vaccination programs in Thailand, China, Vietnam, and India, and large-scale vaccine demonstration projects in five Asian countries that have confirmed the effectiveness of vaccines for reducing typhoid in endemic, highincidence settings. 11,[18][19][20][21] Typhoid vaccination can also be considered in other high-incidence settings, along with comprehensive typhoid control measures. …”

Section: Discussionmentioning

confidence: 99%

Impact of a Targeted Typhoid Vaccination Campaign Following Cyclone Tomas, Republic of Fiji, 2010

Scobie¹,

Nilles²,

Kama³

et al. 2014

The American Society of Tropical Medicine and Hygiene

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Abstract. After a category 4 cyclone that caused extensive population displacement and damage to water and sanitation infrastructure in Fiji in March 2010, a typhoid vaccination campaign was conducted as part of the post-disaster response. During June-December 2010, 64,015 doses of typhoid Vi polysaccharide vaccine were administered to persons 2 years of age, primarily in cyclone-affected areas that were typhoid endemic. Annual typhoid fever incidence decreased during the post-campaign year (2011) relative to preceding years (2008)(2009) in three subdivisions where a large proportion of the population was vaccinated (incidence rate ratios and 95% confidence intervals: 0.23, 0.13-0.41; 0.24, 0.14-0.41; 0.58, 0.40-0.86), and increased or remained unchanged in 12 subdivisions where little to no vaccination occurred. Vaccination played a role in reducing typhoid fever incidence in high-incidence areas after a disaster and should be considered in endemic settings, along with comprehensive control measures, as recommended by the World Health Organization.

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Typhoid vaccination: the Asian experience

Cited by 41 publications

References 19 publications

A Study on Longevity of Immune Response after Vaccination with Salmonella Typhi Vi Conjugate Vaccine (Pedatyph™) in Children

A Study on Longevity of Immune Response after Vaccination with Salmonella Typhi Vi Conjugate Vaccine (Pedatyph™) in Children

Physical and Chemical Characterization and Immunologic Properties ofSalmonella entericaSerovar Typhi Capsular Polysaccharide-Diphtheria Toxoid Conjugates

Impact of a Targeted Typhoid Vaccination Campaign Following Cyclone Tomas, Republic of Fiji, 2010

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