Fractional Dosing of Yellow Fever Vaccine to Extend Supply: A Modeling Study

Joseph T. Wu; Corey M. Peak; Gabriel M. Leung; Marc Lipsitch

The evidence base for fractional-dose YF vaccines is built upon two studies that compared the 82 safety and immunogenicity of standard-dose and five-fold fractional-dose YF vaccines. The first 83 is a randomized, noninferiority trial which showed that 0·1 ml intradermal (ID) vaccination with 84 the 17D YF vaccine was equally safe and immunogenic compared to the standard 0·5ml 85 subcutaneous vaccination. 8 We estimate the initial reproductive number of the YF outbreak in Angola as the average 138 reproductive number among all cases who developed symptoms one serial interval before 139 vaccination campaign began to affect disease transmission (see Figure 1 ). fractionation, we assume that vaccine efficacy of n-fold fractional-dose vaccines for n between 150 1 and 5 increases linearly with the amount of antigen in the vaccines (see appendix for 151 explanation). Potential increases in vaccine wastage during dose-sparing would be mostly due 152