Measles and rubella are rash illnesses that typically afflicted young children in the pre-vaccination era,but rubella usually is mild while measles may be severe. As childhood vaccines commonly includeantigens to the viruses causing both diseases, vaccination programs must be designed to attain disparate goals: prevent measles among young children and rubella among young women. By virtue of increasingly effective routine vaccination, together with targeted supplemental immunization activities (SIAs), health authorities in the People’s Republic of China have reduced measles’ reproduction number from about 18 to 2.3. To support global eradication efforts, as well as expedite morbidity and mortality reductions in China, we evaluated alternative SIAs via mechanistic mathematical modeling. The model includes a function by which contacts between members of different groups are a mixture of preferential and proportionate with respect to age, but decline exponentially with distance at agedependent rates. We estimated initial conditions and most parameters from recent cross-sectional serological surveys, disease surveillance and demographic observations. Then we evaluated the effective reproduction numbers and their partial derivatives with respect to sub-population immunization rates. We corroborated our analytical results by simulating adolescent and young adult SIAs using a deterministic model with seasonally-forced person-to-person contact rates. The results indicate theimportance of indirect effects (i.e., fewer infections than vaccinated people might otherwise cause), which meta-population models with realistic mixing are uniquely capable of reproducing accurately.
星期四, 2018/07/12 - 从 16:00 到 17:30
Zhilan Feng 教授