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Typhoid conjugate vaccine (TCV) is now preferred over other vaccine types, and the World Health Organization (WHO) recommends its introduction be prioritized in regions with the highest burden of typhoid fever and/or a high burden of antimicrobial-resistant Salmonella Typhi, according to a new WHO position paper published in Vaccine.
As there are higher and more sustained levels of immunogenicity from 1 dose of injectable Vi-TT (tetanus toxoid) conjugate vaccine (Typbar-TCV) compared with the injectable Vi polysaccharide vaccine (ViPS) vaccine, WHO recommends TCV as a 0.5-mL single dose for infants and children aged 6 months and older and for adults aged up to 45 years in typhoid endemic regions.
If ViPS is used, a single dose should be administered to those aged 2 years and older, and for the Ty21 vaccine, a 3-dose oral immunization schedule is recommended at >6 years.
For catch-up vaccination, TCV is recommended up to 15 years of age, when feasible, and is supported by epidemiologic data, such as the burden of disease.
WHO recommends vaccination in cases of confirmed outbreaks of typhoid fever, although data on the use of vaccines in controlling outbreaks are very limited, and research to assess the value of vaccination in these cases is strongly recommended. Also outlined are recommendations for the vaccination of special populations, as well as contraindications and precautions that need to be taken.
“Priority should be given to generating data that will further support typhoid vaccination policy and immunization programmes,” concluded the authors, and research is particularly needed in a number of areas, including the development of tools or methods to identify populations and individuals at risk for typhoid fever and the risk for transmission from chronic carriers, as well as strategies to identify and treat carriers.
Reference
World Health Organization. Typhoid vaccines: WHO position paper, March 2018 – recommendations [published online April 13, 2018]. Vaccine. doi: 10.1016/j.vaccine.2018.04.022
