An Agent-Based Model of School Closing in Under-Vaccinated Communities during Measles Outbreaks.

Monday, 3rd of October 2016

Agent Dir Simul Symp. 2016 Apr;2016. pii: 10.

An Agent-Based Model of School Closing in Under-Vaccinated Communities during Measles Outbreaks.

Getz WM¹ Carlson C² Dougherty E² Porco Francis TC 1st³ Salter R⁴.

Author information

Abstract

The winter 2014-15 measles outbreak in the US represents a significant crisis in the emergence of a functionally extirpated pathogen. Conclusively linking this outbreak to decreases in the measles/mumps/rubella (MMR) vaccination rate (driven by anti-vaccine sentiment) is critical to motivating MMR vaccination. We used the NOVA modeling platform to build a stochastic spatially-structured individual-based SEIR model of outbreaks under the assumption that R ₀ ≈ 7 for measles. We show this implies that herd immunity requires vaccination coverage of greater than approximately 85%. We used a network structured version of our NOVA model that involved two communities one at the relatively low coverage of 85% coverage and one at the higher coverage of 95% both of which had 400-student schools embedded as well as students occasionally visiting super spreading sites (e.g. high-density theme parks cinemas etc.). These two vaccination coverage levels are within the range of values occurring across California counties. Transmission rates at schools and super spreading sites were arbitrarily set to respectively 5 and 15 times background community rates. Simulations of our model demonstrate that a send unvaccinated students home policy in low coverage counties is extremely effective at shutting down outbreaks of measles.