Background: Measles is resurgent in the US, with more cases in 2019 than any year since 1992. Many of the cases were concentrated in three outbreaks in New York and Washington states, where local governments enacted intervention strategies in an attempt to limit the spread of measles. Regulations differed by location, suggesting guidance on the optimal interventions may be beneficial.
Methods: We simulate the daily interactions of the populations of six metropolitan areas of Texas, US, using an agent-based model. The real-life vaccination rates of each school in these metropolitan areas are applied to simulated equivalents. A single case of measles is introduced to the population and the resulting number of cases counted. A range of public health interventions, focused on suspending unvaccinated students and mandatory vaccinations, were simulated during measles outbreaks and the reduction in the number of measles cases, relative to no intervention, recorded. Interventions were simulated only in schools with measles cases and in all schools in each metropolitan area.
Results: Suspending unvaccinated students from school was associated with the greatest reduction in measles cases. In a plausible worst-case outbreak scenario, the number of cases is forecast to reduce by 68-96%. Interventions targeting all schools in a metropolitan area is not found to be associated with fewer measles cases than only targeting schools with measles cases, at 2018 vaccination rates. Targeting all schools also increases the cumulative number of school days missed by suspended students by a factor of 10-100, depending on the metropolitan area, compared to targeting only schools with measles cases. If vaccination rates drop 5% in the schools which are under-vaccinated in 2018, metropolitan area-wide interventions are forecast to be associated with fewer cases than school-specific interventions.
Conclusions: Interventions that are quickly implemented and widely followed may reduce the size of measles outbreaks by up 96%. If vaccination rates continue to fall in Texas, metropolitan area-wide interventions should be considered in the event of an outbreak.
Key Take Away Points
Suspending unvaccinated students from schools is associated with a 68-96% reduction in measles cases compared to no intervention, in a plausible worst-case outbreak.
Vaccinating students during an outbreak is also associated with a reduction in measles cases, but is less successful than school suspensions.
Interventions targeting all schools in a metropolitan area are not found to be associated with fewer measles cases than only targeting schools with measles cases, at 2018 vaccination rates.
David Sinclair, PhD, is a postdoctoral research associate at Newcastle University, UK. John Grefenstette, PhD, is a Professor in the Department of Health Policy and Management and Senior Scientist in the Public Health Dynamics Laboratory, at the University of Pittsburgh, US. Mary Krauland, PhD, is a Visiting Research Assistant Professor in the Department of Health Policy and Management, and the Public Health Dynamics Laboratory, at the University of Pittsburgh, US. David Galloway, MS, is a Research Programmer in the Public Health Dynamics Lab at the University of Pittsburgh, US. Robert Frankeny, MSIS, is a Systems Programmer in the Public Health Dynamics Lab at the University of Pittsburgh, US. Clayton Travis, MSSW, is Director of Advocacy and Health Policy of the Texas Pediatric Society, the Texas Chapter of the American Academy of Pediatrics, Austin, Texas. Donald Burke, MD, is Distinguished University Professor of Health Science and Policy, Epidemiology, Jonas Salk Chair in Population Health, Epidemiology, and Dean Emeritus, Graduate School of Public Health, at the University of Pittsburgh, US. Steven Albert, PhD, is Professor and Chair, Behavioral and Community Health Sciences, and Philip B. Hallen Endowed Chair in Community Health and Social Justice, at the University of Pittsburgh, US Mark Roberts, MD, MPP, is Professor and Chair, Health Policy and Management, and Director, Public Health Dynamics Lab, at the University of Pittsburgh, US.
Sinclair, David R.; Grefenstette, John J.; Krauland, Mary G.; Galloway, David D.; Frankeny, Robert J.; Travis, Clayton; Burke, Donald S.; Albert, Steven M.; and Roberts, Mark S.
"Interventions in measles outbreaks: the potential reduction in cases associated with school suspension and vaccination interventions,"
Journal of Applied Research on Children: Informing Policy for Children at Risk: Vol. 10:
2, Article 10.
Available at: https://digitalcommons.library.tmc.edu/childrenatrisk/vol10/iss2/10