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

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

We use the Wallinga and Teunis method 13 to estimate the reproductive number over the course of the YF outbreak in Angola from the daily number of confirmed cases recorded in the 17 April 2016 WHO Angola Situation Report. 14 We assume that all cases were attributed by local transmission, i.e. no importation of cases. Let t i be the date of symptom onset for case i. The relative likelihood that case i has been infected by case j is where w(·) is the probability density function of the serial interval. Assuming that the probability of case j infecting case i is independent of the probability of case j infecting any other case, the reproductive number for case j is a Bernoulli random variable with mean ∑ i p ij . The reproductive number on day t, namely R t , is approximated as the average of the reproductive number of all cases who have symptom onset on day t, in which case the mean and standard deviation of R t are