Extensively Drug-Resistant Typhoid — Are Conjugate Vaccines Arriving Just in Time?

OBJECTIVE:
In Hyderabad, Pakistan, an outbreak of extensively drug-resistant (XDR) Salmonella enterica ssp. enterica serovar Typhi, resistant to chloramphenicol, ampicillin, trimethoprim–sulfamethoxazole, fluoroquinolones, and third-generation cephalosporins, was recognized in November 2016 and has now spread to Karachi, home to more than 14 million people. More than 1000 cases have been confirmed by blood culture; since most typhoid cases are treated empirically, however, the true number of cases is probably many times greater.
RESULTS:
The Typbar TCV vaccine is now being used in the outbreak response in Hyderabad, though the strain had already spread beyond the vaccine target area and may continue to disseminate. The new WHO recommendation, availability of a prequalified vaccine with durable immunogenicity that can be given to young children, and the Gavi funding commitment provide more favorable conditions than have ever before existed for countries to incorporate typhoid vaccines into immunization programs. To guide these efforts, we need to invest in improved surveillance efforts and accelerate conjugate vaccine introduction in countries where the burden of typhoid is known to be high. Whether we will take the necessary action before the window closes is still uncertain.

Click here to view the article, published in The New England Journal of Medicine.