Factors Associated With Measles Infection in Afghanistan Surrounding the 2021 Outbreak: A Multivariable Analysis

Despite development of a safe and effective vaccine, measles remains a risk in many low-income countries where vaccination is less available. Afghanistan's recent measles epidemic remains understudied, and data are needed to inform the public health response. This study investigated the demographic and epidemiologic characteristics associated with suspected and laboratory-confirmed measles infections surrounding the 2021 outbreak in Afghanistan.

We conducted a multivariable retrospective analysis of historical measles case data in Afghanistan from July 2019 to June 2023.

Confirmed measles infections in Afghanistan increased by >200% since July 2021, and the majority of cases during the recent outbreak were laboratory-confirmed. Early infancy was a risk factor for confirmed measles during the recent outbreak, as compared with pre-outbreak (P < .001). Epidemiologic linkage was identified as protective (P < .001), while sex (P = .796) and travel history (P = .615) were not predictive of risk.

Routinely collected measles surveillance data suggest that infancy and unknown travel status posed greater risk to those with confirmed measles infection in Afghanistan during the 2021 epidemic as compared with pre-epidemic, and known exposure may lead to lower rates of formal laboratory diagnosis. The results also highlight the geographic shift in cases before vs during the outbreak, as well as differences in distribution of suspected and laboratory-confirmed cases throughout the epidemic.