Determining the Best Immunization Strategy for Protecting African Children Against Invasive <i>Salmonella</i> Disease

다국어 초록 (Multilingual Abstract)

<▼1><P><B>Abstract</B></P><P><B>Background</B></P><P>The World Health Organization recently prequalified a typhoid conjugate vaccine (TCV), recommending its use in persons ≥6 months to 45 years residing in typhoid fever (TF)–endemic areas. We now need to consider how TCVs can have the greatest impact in the most vulnerable populations.</P><P><B>Methods</B></P><P>The Typhoid Fever Surveillance in Africa Program (TSAP) was a blood culture-based surveillance of febrile patients from defined populations presenting at healthcare facilities in 10 African countries. TF and invasive non-typhoidal <I>Salmonella</I> (iNTS) disease incidences were estimated for 0–10 year-olds in one-year age increments.</P><P><B>Results</B></P><P><I>Salmonella</I> Typhi and iNTS were the most frequently isolated pathogens; 135 and 94 cases were identified, respectively. Analysis from three countries was excluded (incomplete person-years of observation (PYO) data). Thirty-seven of 123 TF cases (30.1%) and 71/90 iNTS disease cases (78.9%) occurred in children aged <5 years. No TF and 8/90 iNTS infections (8.9%) were observed in infants aged <9 months. The TF incidences (/100 000 PYO) for children aged <1 year and 1 to <2 years were 5 and 39, respectively; the highest incidence was 304 per 100 000 PYO in 4 to <5 year-olds. The iNTS disease incidence in the defined age groups ranged between 81 and 233 per 100 000 PYO, highest in 1 to <2 year-olds. TF and iNTS disease incidences were higher in West Africa.</P><P><B>Conclusions</B></P><P>High burden of TF detected in young children strengthens the need for TCV introduction. Given the concurrent iNTS disease burden, development of a trivalent vaccine against <I>S.</I> Typhi, <I>S.</I> Typhimurium, and <I>S.</I> Enteritidis may be timely in this region.</P></▼1><▼2><P>A significant burden of typhoid fever in children aged <5 years in sub-Saharan Africa merits the introduction of typhoid conjugate vaccine at age 9 months, which coincides with the first dose of measles vaccine.</P></▼2>