Early measles vaccination for infants younger than 12 months has gained increasing attention as global measles resurgence has widened the immunity gap before the recommended age for routine immunization. Although the World Health Organization (WHO) recommends the first dose of measles-containing vaccine (MCV1) at 9 months in high-transmission settings and 12 months in low-transmission settings, declining maternal antibodies and suboptimal vaccination coverage leave many infants susceptible well before reaching the recommended vaccination age. Consequently, an early supplementary dose (MCV0) has been introduced in specific high-risk situations, including outbreaks, traveling to outbreak areas, HIV exposure, humanitarian crises, and other settings with elevated transmission risk.
Current evidence indicates that maternal antibody levels fall below protective thresholds within the first few months of life, particularly those born to vaccinated mothers, whose antibody levels decline earlier than those born to naturally immune mothers. This creates a window of vulnerability before routine immunization. However, the immune response to vaccination before 12 months is influenced by immature immune function and residual maternal antibodies, which may reduce antibody production compared with vaccination at older ages Overall, evidence suggests that vaccination at 9\u201312 months induces stronger and more durable immunity than vaccination before 9 months.
Despite these immunological limitations, early measles vaccination provides substantial short-term protection during outbreaks. Studies from Canada and Guinea-Bissau showed high vaccine effectiveness in preventing measles infection among infants vaccinated before 12 months of age. Although some studies reported lower long-term antibody levels following vaccination at younger ages, generally boosted immunogenicity and often restored protective antibody levels, although long-term findings remain mixed. These findings support the role of MCV0 as a supplementary intervention rather than a replacement for the standard two-dose vaccination series.
Safety evidence is similarly reassuring. Clinical trials, observational studies, and systematic reviews consistently demonstrate that early measles vaccination is well tolerated, with adverse events generally mild and comparable to those observed following routine vaccination. Serious adverse events were rare and were generally considered unrelated or unlikely to be related to vaccination, supporting the safety of administering MCV0 in appropriate high-risk settings.
Overall, the available evidence suggests that early measles vaccination is an effective strategy for protecting vulnerable infants during outbreaks and other high-risk circumstances while maintaining the importance of completing the routine immunization schedule. Strengthening routine vaccination coverage, ensuring accurate documentation of supplementary doses, identifying zero-dose children, and improving vaccine accessibility for mobile and underserved populations remain essential to sustaining measles elimination efforts and reducing disease burden among young infants.<\/p>\n\n\n\n
Relevant Research:
AlSaihati A, Chaudhary M, Olarte L. Early Measles Vaccination in Infants Less than 12 Months: Global Practices, Immunity Outcomes, and Implications for Disease Prevention. Journal of the Pediatric Infectious Diseases Society. 2026;15(4):1\u20139. doi:10.1093\/jpids\/piag018<\/p>\n\n\n\n
Translating and summarizing: Tianyi Deng
Reviwer: Ziqi Liu
Page editor : Ruitong Li<\/p>\n","protected":false},"excerpt":{"rendered":"
Early measles vaccination for infants younger than 12 months has gained increasing attention as global measles resurgence has widened the immunity gap before the recommended age for routine immunization. Although the World Health Organization (WHO) recommends the first dose of measles-containing vaccine (MCV1) at 9 months in high-transmission settings and 12 months in low-transmission settings, […]<\/p>\n","protected":false},"featured_media":16694,"menu_order":0,"template":"","meta":{"type_label":"none_selected"},"news-category":[73],"class_list":["post-16824","project-news","type-project-news","status-publish","has-post-thumbnail","hentry","news-category-research-en"],"_links":{"self":[{"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/project-news\/16824","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/project-news"}],"about":[{"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/types\/project-news"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/media\/16694"}],"wp:attachment":[{"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/media?parent=16824"}],"wp:term":[{"taxonomy":"news-category","embeddable":true,"href":"https:\/\/vaxlab.dukekunshan.edu.cn\/en\/wp-json\/wp\/v2\/news-category?post=16824"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}