The Lancet Infectious Diseases
Feb 2014  Volume 14  Number 2 p87 – 172
http://www.thelancet.com/journals/laninf/issue/current

Editorial
A conjugate vaccine against typhoid fever
Se Eun Park, Florian Marks
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Zulfiqar Bhutta and colleages’ study1 in The Lancet Infectious Diseases marks an important milestone for the use of typhoid conjugate vaccines. Present Vi polysaccharide vaccines (Vi-PS) are not widely used because they cannot be given to children younger than 2 years and are thus excluded from the Expanded Programme of Immunization (EPI); furthermore, their effectiveness decreases rapidly after 2–3 years.2,3 Expectations of a typhoid conjugate vaccine include safe administration to children younger than 2 years, the induction of protective IgG anti-Vi immune responses, and the development of long-term, and at best lifelong, protection.