Abstract
BACKGROUND: Improved immunization rates have reduced the incidence of vaccine-preventable diseases (VPDs) in advanced nations. Japan's unique vaccination system classifies vaccines into routine vaccines ostensibly required under the Preventive Vaccination Law and recommended but optional vaccines, although all vaccines are in fact voluntary. In Japan, low immunization rates, particularly for optional vaccines, have resulted in high rates of sequelae and death. The decision as to whether a child will receive a vaccine depends on the parents, who must obtain information, make inquiries, and make the required payment, the last of which is a major barrier. This randomized, controlled trial was conducted to evaluate the effectiveness of an immunization education program designed to meet mothers' needs. METHODS: This randomized controlled trial assigned pregnant women to intervention or control groups. The intervention was individual education sessions involving the children's fathers in shared decision-making on whether or not to immunize their child. A survey was conducted before and after the intervention. Data were analyzed using the intention-to-treat principle. RESULTS: Of 225 pregnant women, 175 (78%) participated and 171 replied to the post-survey. At age 3 months, intervention infants had higher self-reported immunization rates for hepatitis B virus vaccine (76% vs. 49%; P < 0.001) and rotavirus vaccine (84% vs. 68%; P = 0.019) than control group infants. The percentage of parents intending to vaccinate their infants was higher in the intervention group (77% vs. 52%; P < 0.01). Improvements in scores for basic knowledge (mean [SD]: 5.5 [3.6] vs. 3.0 [3.8], range: 10-30; P < 0.001), advanced knowledge (mean [SD]: 5.1 [2.4] vs. 2.8 [2.5], range: 5-15; P < 0.001), and health literacy regarding immunization (mean [SD]: 0.5 [0.8] vs. 0.2 [0.6], range: 1-5; P < 0.01) were higher in the intervention group. The rate of decision making by both parents (68% vs. 52%; P < 0.05) was higher in the intervention group. CONCLUSIONS: Our findings confirmed the program's effectiveness. The intervention improved immunization rates, the percentage of parents intending to vaccinate their infants and knowledge scores. Interventions which directly and indirectly involved fathers in shared decision-making on whether to immunize their child were effective, as were individualized interventions that provided parents with access to up-to-date information. TRIAL REGISTRATION: UMIN000012575 . Registered 14 December 2013 (The study was prospectively registered).