A systematic review to guide measles exposure periods for contact tracing.

Abstract

<h4>Background</h4>This systematic review examined the duration of measles virus airborne transmissibility after a source case is no longer present to identify evidence gaps in measles contact tracing exposure window guidelines.<h4>Methods</h4>A 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 editorials, opinion pieces, non-evidence-based recommendations, mathematical models, and publications unrelated to airborne transmission of measles in public environments or not available in English were excluded. Researchers extracted summary data.<h4>Findings</h4>Initial database searches identified 1054 studies, with none meeting initial inclusion criteria after screening. Supplemental searches identified five relevant articles (1964-1987). Two experimental studies and three real-world studies demonstrated measles virus survival between 29 and 120 min, with increasing survival time for lower humidity levels.<h4>Interpretation</h4>Current guidelines for measles contact tracing exposure windows rely on limited research from 1964 to 1987. Additional studies are urgently 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.<h4>Funding</h4>U.S. Centers for Disease Control & Prevention (Cooperative Agreement #NU38FT000004).