Measles Humoral and Cell-Mediated Immunity in Children Aged 5-10 Years After Primary Measles Immunization Administered at 6 or 9 Months of Age

摘要

Measles remains the leading cause of vaccine-preventable childhood mortality globally despite substantial declines through immunization programs [1]. In 2008, 164 000 measles-related deaths occurred [2], with the highest fatality rates seen during the first year of life [3]. Although disease burden is greatest in developing nations, the changing epidemiology of measles in developed countries is a concern [2-12]. The United States was declared free from endemic measles transmission in 2000; nevertheless, cases continue to be imported [5, 6, 11, 12]. The year 2008 saw the highest measles incidence since 1998 (131 cases), and 21% of cases were in children younger than the recommended age for primary vaccination, with these children representing 26% of measles hospitalizations [4]. Of the 222 cases of measles in the United States in 2011, 90% of the cases were imported, and 14% of the cases occurred in infants aged <12 months [5]. Control of measles in the United States is complicated by a shift to an earlier loss of transplacentally acquired measles antibodies in infants [8-10]. In the United States, approximately 40% of infants aged 6 months lack passive antibodies (PAs) against measles [7, 8, 12] and remain vulnerable to infection until they are immunized.