Typhoid conjugate vaccine effectiveness in Malawi: evaluation of a test-negative design using randomised, controlled clinical trial data.

Liang Y, Driscoll AJ, Patel PD, Datta S, Voysey M, French N, Jamka LP, Henrion MYR, Ndeketa L, Laurens MB, Heyderman RS, Gordon MA, Neuzil KM,