Sustainable Development Goals and childhood measles vaccination in Ekiti State, Nigeria: Results from spatial and interrupted time series analyses

Abstract

Measles remains an important cause of childhood mortality in many resource-limited countries. With Sustainable Development Goals (SDG), there has been increasing emphasis on measles vaccination as a key strategy to remarkably improve child survival. While progress has been made towards measles vaccination coverage due to SDG in some settings, there has been no prior study evaluating its impact in Nigeria. To assess the effectiveness of SDG policy implementation on measles vaccination coverage, we examined the changes in first dose of measles vaccination coverage rates among children aged 9–15 months following the implementation of SDG, and changes in spatial patterns of measles vaccination from 2014 to 2019 in Ekiti State, Southwest Nigeria. Using state and local government area-level District Health Information data from January 2014 to December 2019, we conducted interrupted time series (ITS) and spatiotemporal analyses. The ITS evaluated the immediate and continuous effects of SDG policy implementation on the monthly childhood measles vaccination coverage by comparing longitudinal changes in rates between pre-intervention period (January 2014-December 2015) and during-intervention period (January 2016-December 2019). The low and high coverage clusters across the years were detected with spatial cluster analysis. The average state-level measles vaccination coverage rates from 2014 to 2019 was 70.67%. In 2019, coverage rate was 49%—a 35.53% decline from 76% in 2014 and a state-level gap of 46%. The geographical distribution of measles vaccination varied considerably across the local government areas from 2014 to 2019. There was an initial acceleration of vaccination rates (β^ = 24.07, p-value = 0.012), but a significant decrease in coverage rates after implementation of SDG policy in Ekiti State (β^ = −1.08, p-value < 0.001). No local government area had accelerated monthly coverage rates following SDG-implementation. Evidence suggests immediate acceleration in coverage rates which could not be sustained during SDG-era and calls for a rethink measles immunization coverage strategy in the state and other resource-limited jurisdictions to ensure vaccination scale-up.