Hidden Burden of a Measles Outbreak Revealed by Genomic and Transmission Models

Area of Science:

• Epidemiology
• Public Health
• Infectious Disease Modeling

Background:

• Declining childhood vaccination rates have led to a resurgence of measles in the U.S.
• Current surveillance systems may underestimate the true extent of measles outbreaks.
• A large ongoing outbreak along the Utah-Arizona border is characterized by high vaccine exemption rates and limited healthcare engagement.

Purpose of the Study:

• To quantify the true size of the measles outbreak along the Utah-Arizona border.
• To assess the extent of underreporting in measles surveillance.
• To evaluate the utility of complementary analytical approaches in understanding disease transmission.

Main Methods:

• Phylodynamic analysis of viral genetic data.
• Agent-based modeling simulating disease spread.
• Comparison of model outputs with reported case data.

Main Results:

• Both phylodynamic and agent-based models indicated significant underreporting of measles cases.
• The true outbreak size was estimated to be 3.1- to 4.8-fold larger than reported.
• Confirmed measles cases represented only 20.96%-32.5% of total infections.

Conclusions:

• Substantial underreporting of measles occurs, particularly in close-knit communities with low vaccination coverage.
• Complementary analytical methods are crucial for accurately assessing measles transmission.
• Improved surveillance and reporting are essential for effective measles control efforts.