A Systematic Review of Measles Virus Transmissibility in the Air to Guide Exposure Periods for Contact Tracing in Public Spaces

ObjectivesTo systematically review epidemiological evidence to determine how long the measles virus remains transmissible after an infectious case leaves a public space to address inconsistencies in measles contact tracing exposure window guidelines. MethodsA systematic literature review following PRISMA guidelines was conducted using PubMed, EMBASE, Web of Science, and SCOPUS databases for publications from January 1988 to July 2024. Additional sources were identified through reference list reviews and Google Scholar searches. Studies examining how long the measles virus survives in the air or remains transmissible after an infectious case leaves a public space were included, while non-evidence-based recommendations and mathematical models were excluded. ResultsInitial database searches identified 1,054 studies, with none meeting initial inclusion criteria after screening. Supplemental searches identified five relevant articles (1964-1987). Two experimental studies demonstrated measles virus survival between 30 and 120 minutes, with increasing survival time for lower humidity levels. Experimental studies showed survival at two hours in low humidity (12-15%), up to 60 minutes in moderate humidity (36-37%), and 30 minutes in high humidity (60-70%) at 20{degrees}C. Three publications reviewed how long measles virus was transmissible in real-world settings, ranging from 60 to 120 minutes. ConclusionsLimited evidence exists to guide the precise determination of the duration of measles transmissibility. Current health department guidelines rely on limited research from 1964 to 1987. Additional studies are needed to understand how long the virus is transmissible in real-world settings, particularly given the implications for contact tracing efficiency and resource allocation during outbreak responses.