A new study found that young healthcare personnel (HCP) were less likely to have detectable measles antibodies due to either declining vaccination rates or significant waning of vaccine-induced immunity.
Although measles was essentially eliminated in the United States 20 years ago, a resurgence in the number of cases has prompted a nationwide intensification of measles-specific prevention measures. From 2001 to 2014, 78 measles cases were reported in US healthcare facilities, including 29 HCP, 19 of whom had presumptive evidence of immunity as determined by criteria established by the Centers for Disease Control and Prevention (CDC).
Presumptive evidence of immunity based on CDC criteria is either 2 doses of the measles, mumps, and rubella (MMR) vaccine for HCP born in 1957 or later OR 2 positive measles immunoglobulin G (IgG) antibody test results. According to the CDC, only 10 states have enacted laws requiring HCP to demonstrate immunity to MMR. Although large seroprevalence studies conducted on US HCP in the 1990s showed that approximately 6.5% of HCP lacked measurable measles antibodies, similar assessments for US HCP born after 1985 who would have received 2 MMR doses in childhood are lacking. Therefore, at Memorial Sloan Kettering Cancer Center (MSKCC) in New York City, a team of researchers determined the age-specific seroprevalence of measles antibody in a large cohort of newly employed HCP.