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

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

Reproductive number of yellow fever in Angola. Figure 1 shows that the initial reproductive 223 number of YF in Angola was 5·2 (95% CI 4·3, 6·1) and 7·1 (5·5, 8·7) if the mean mosquito 224 lifespan was 7 and 14 days, respectively. While these estimates may reflect partial immunity 225 due to prior vaccination or exposure among some of the population (we estimated that around 226 28% of the Angola population had been vaccinated before the YF epidemic; see appendix for 227 calculation details), we assume that the basic reproductive number of a future outbreak in 228 another population would range between 4 and 12 due to varying vector ecology and levels of 229 preexisting immunity in the population. 230 Figure 2A The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It . https://doi.org/10.1101/053421 doi: bioRxiv preprint for R 0 = 4 and 8, respectively). In short, dose fractionation reduces IAR when (i) the standard-239 dose vaccine supply is insufficient to halt disease transmission and (ii) fractional-dose vaccine 240 efficacy is above 0·2. 241