Vaccine shot-limiting: Estimating the prevalence, indicators, and impact on vaccination status - Michigan, 2012.

BACKGROUND: Concerns regarding vaccine safety and pain have prompted certain parents to limit the number of shots their child receives per visit. We estimated the prevalence of shot-limited children in Michigan, described their characteristics, assessed whether shot-limited children were up-to-date on recommended vaccinations, and investigated possible intervention points for vaccination education.

METHODS: We analyzed vaccination registry and birth record data of children born in Michigan during 2012 who had ⩾2 vaccination visits, with ⩾1 visits after age 5months. Shot-limited was defined as receiving ⩽2 shots at all visits through age 24months. Nonlimited children received >2 shots at ⩾1 visits. Up-to-date vaccination was based on receipt of a seven-vaccine series and was determined at ages 24months and 35months. Risk ratios (RR) were calculated using risk regression.

RESULTS: Of 101,443 children, a total of 2,967 (3%) children were shot-limited. Mothers of shot-limited children were more likely to be white (RR: 1.2; 95% confidence interval [CI]: 1.2-1.2), college graduate (RR: 1.9; 95% CI: 1.9-2.0), and married (RR: 1.5; 95% CI: 1.5-1.5). Compared with nonlimited children, shot-limited children were more likely to be born in a nonhospital setting (RR: 11.7; 95% CI: 9.4-14.6) and have a midwife attendant (RR: 1.9; 95% CI: 1.7-2.1). Shot-limited children were less likely to be up-to-date on recommended vaccinations (RR: 0.2; 95% CI: 0.2-0.3); this association was stronger for those with a midwife birth attendant (RR: 0.1; 95% CI: 0.1-0.2) rather than a medical doctor (RR: 0.3; 95% CI: 0.2-0.3).

CONCLUSIONS: Shot-limited children are less likely to be up-to-date on vaccinations, possibly leading to increased risk for vaccine-preventable diseases. This association was stronger for those with a midwife birth attendant. This analysis should prompt targeted education, such as to midwives, concerning risks associated with shot-limiting behavior.