Vaccine Coverage at 36 Months and 7 Years by Parental Birth Country, Washington State

To understand determinants of vaccination among immigrant communities at a community level to design and support public health interventions in order to improve immunization rates among diverse ethnic groups.The study evaluated children born in Washington state between January 1, 2006, and November 12, 2019. In total, the study included 902 909 children who met the inclusion criteria at 36 months and 646 746 children who met the inclusion criteria at 7 years.This retrospective medical record review compared vaccination outcomes in children at age 36 months and 7 years based on parental country of origin. They matched medical records from the Washington State Immunization Information System and Washinton Canter for Health Statistics Birth Certificate Records by birth certificate ID. The primary outcome was the measles, mumps, and rubella (MMR) status at 36 months, and the secondary outcome was the status of Diptheria Tetanus and acellular Pertusis (DTaP) and poliovirus vaccination at 36 months and 7 years. Further subanalysis was conducted to better understand country-level trends. Descriptive statistics were used to outline the relationship between parental birth country and vaccine status. Covariates included in the multivariable models included maternal education, number of prenatal visits, Women, Infants and Children (WIC) benefits, and insurance status.Among the children who met inclusion criteria, 24% (n = 219 378) had at least 1 non–US-born parent. When comparing children with US-born parents, MMR status at 36 months was 3% to 10% higher for children with at least 1 parent born in India, Philippines, or Mexico. However, it was found that the MMR status at 36 months was 8% to 22% lower for children with at least 1 parent born in Micronesia, Marshall, Romania, or Somalia and even 35% to 51% lower for children with a parent born in Moldovia, Russia, and Ukraine. Between 2009 and 2022, vaccination coverage declined between the ranges of 13% and 47.2% at 36 months among children of Marshallese-, Russian-, Romanian-, Moldovan-, Ukrainian-, and Somali-born parents. Similar country-level trends at the 36-month mark were noticed at age 7 years. However, there was less magnitude of difference for MMR vaccination status between children of Somali-born parents and children of US-born parents. It is noted that at age 7 years, only 14.1% of children with Somali-born parent(s) remained unvaccinated whereas 41.3% children of Ukrainian-born parent(s) remained unvaccinated at 7 years.By linking birth and immunization records, this study was able to highlight community-level vaccination data. The vaccination trends among children of non–US-born parent(s) provides information about community-level determinants of vaccination and can help create community-informed interventions.This study is not only helpful in informing public health efforts but timely given ongoing antivaccination efforts and a recent rise in vaccine-preventable diseases. It will be important to identify how cultural influences and parental perceptions differ among various countries of origin and design interventions to address these variables.