Utility of MF-non coding region for measles molecular surveillance during post-elimination phase, Spain, 2017-2020.

Our results show the ability of the proposed method to improve identification of simultaneous importations in the same region which could trigger enhanced contact tracing. Moreover, the identification of further transmission chains indicates that the size of import-related outbreaks was smaller than previously found, supporting the interpretation that endemic measles transmission was absent in Spain between 2017 and 2020. We suggest considering the use of the MF-NCR region in conjunction with the study of N450 variants in future WHO recommendations for measles surveillance.