Results
non-typhoid illness, non-typhoid, typhoid fever, typhoid
TYPHOID FEVER, TYPHOID
The study sample derivation is shown in Study sample derivationCompared with children in the non-test-negative design sample (Participant baseline characteristics by availability of blood culture specimensData are n (%), unless otherwise indicated. MenA=meningococcal capsular group A conjugate vaccine. Vi-TT=typhoid Vi polysaccharide-tetanus toxoid-conjugate vaccine.Vaccine efficacy against typhoid fever in the randomised trial up to September, 2021 (ie, at least 3 years after vaccination), was 80·4% (95% CI 66·4 to 88·5) based on the IRR method and 80·3% (66·3 to 88·4) based on the RR method. For all three test-negative design approaches, vaccine effectiveness estimates (test-negative design A, 80·3% [95% CI 66·2 to 88·5] Influence of vaccine against blood culture-confirmed typhoid and non-typhoid illnesses, estimated by per-protocol and three test-negative design analysis approachesData are n or n/N (%), unless otherwise indicated. MenA=meningococcal capsular group A conjugate vaccine. VE=vaccine efficacy in the randomised controlled trial or vaccine effectiveness in the test-negative design. Vi-TT=typhoid Vi polysaccharide-tetanus toxoid-conjugate vaccine.Cases are typhoid-positive specimens and controls are typhoid-negative specimens.Controls include participants with an episode of non-typhoid illness, without censoring for typhoid (ie, controls might have tested positive for typhoid at another timepoint).Controls include participants with an episode of non-typhoid illness, with censoring for typhoid (ie, controls exclude participants who ever had a test that was typhoid-positive during the study period).VE=(1 – odds ratio) × 100%, using the test-negative design sample only.VE=(1 – incidence rate ratio) × 100%.Test-negative design A.Test-negative design B.Test-negative design C.VE=(1 – risk ratio) × 100%, using the whole randomised controlled trial.Effect of vaccine on blood culture-confirmed typhoid overall and by subgroupsVE=Vaccine efficacy in the randomised controlled trial or vaccine effectiveness in the test-negative design.Subgroup analyses were done by age, sex, and study site (The simulated 1:3 case-control matched test-negative design (101 typhoid-positive specimens Vaccine misclassification might have affected the estimation of vaccine effectiveness in a test-negative design (Effect of overall vaccine misclassification rate (pData are n/N (%), unless otherwise indicated. See the VE=(1 – odds ratio) × 100%.Only misclassifying vaccinated as unvaccinated for both cases and controls due to the loss of vaccination cards, that is, ppp101 (1·2%) of 8161 blood culture specimens were positive for Effect of blood culture test sensitivity on vaccine effectiveness estimation by test-negative design specimen-based analysis, stratified by blood culture positivity rateData are n/N (%), unless otherwise indicated. We assumed the vaccination rate among the false negatives was the same as the vaccination rate among the cases (Adjusted by blood culture sensitivity.VE=(1 – odds ratio) × 100%.