A modern measles outbreak: understanding maternal immunity and impact on postpartum vaccination uptake

In October 2018, a measles (rubeola) outbreak was identified in New York City and Rockland County, and a public health campaign and hospital policy changes were made to increase awareness of the importance of vaccination and increase vaccination rates.

We describe the prevalence of rubeola immunity in pregnant women and the change in uptake of postpartum measles, mumps, and rubella vaccination before and during the measles outbreak.

A multipronged intervention was developed by the health system with the intent of raising awareness of the outbreak, identifying patients at risk of contracting measles during pregnancy, and limiting exposure of inpatients to the disease. This was a quality improvement study to assess the impact of the intervention and public health policy on the rates of documentation of rubeola immunity and rubeola vaccination rates in nonimmune women. Women who delivered at New York University Langone Health before the outbreak July 1, 2016 to July 1, 2017 were compared with women who delivered during the outbreak July 1, 2018 to July 1, 2019. The primary outcome was acceptance of measles, mumps, and rubella vaccination in nonimmune women during the postpartum period. Analysis was conducted using logistic regression and chi-square tests, and alpha was set at 0.05.

A total of 19,585 patients were analyzed; 9162 women delivered before the outbreak and 10,423 delivered during the outbreak. Of these, 2589 (13.2%) were documented as living in a high-risk zone improvement plan code, which were areas at the epicenter of the measles outbreak. Notably, 14,731 women (75.2%) were tested for rubeola immunity and 3270 of those tested (22.2%) were not immune. In the year of the outbreak, a higher proportion of women had rubeola immunity documented with serum titers than in the year before the outbreak (81% vs 69%; P<.001). Inpatient compliance with postpartum measles, mumps, and rubella administration was greater during the outbreak than before it (76% vs 59%; P<.001) for patients from both low-risk and high-risk zone improvement plan codes.

The New York City and Rockland County measles outbreak, together with the implementation of a health system-wide education program and a change in public health policy, led to an increase in the proportion of pregnant women being screened for rubeola immunity. It also led to an increase in uptake of the immediate postpartum measles, mumps, and rubella vaccine.