Method: Parents (N=802) of infants less than 1 year of age responded to an online survey in the United States. Participants were randomized to receive 1 of 4 messages about the MMR vaccine: 1) the Centers for Disease Control and Prevention’s Vaccine Information Statement (CDC VIS); 2) CDC VIS and information emphasizing the MMR vaccine's benefits to the child; 3) CDC VIS and information emphasizing the MMR vaccine's benefits to society; 4) CDC VIS and information emphasizing the MMR vaccine's benefits both to the child and to society. Parents then rated the likelihood of vaccinating their infants on an 11-point response scale ranging from 0 (extremely unlikely) to 100 (extremely likely) in 10-point increments. We also assessed medical trust, as well as attitudes and worries about immunization. We analyzed the data using linear regression models.
Result: Compared to receiving only the CDC VIS, respondents who received additional information emphasizing either 1) the vaccine's benefit to the child or 2) the vaccine's benefits both to the child and to society indicated higher levels of intention to vaccinate their infant for MMR (p=0.01 and p=0.03, respectively). Additional information emphasizing the MMR vaccine's benefits to society did not increase parents’ intentions to vaccinate compared to the CDC VIS alone (p=0.97, ns). Additionally, parents with positive attitudes towards vaccination, high levels of medical trust, or low levels of worry that autism is caused by the MMR vaccine indicated greater vaccine intentions (p<0.01).
Conclusion: Unlike in previous research on adult intentions to be vaccinated, emphasizing additional information about a vaccine's benefits to society (i.e., herd immunity) did not increase parents’ MMR vaccination intentions for their infants. Results suggest that health care providers who want to increase MMR vaccination rates should emphasize the direct benefits of vaccination to the child. Mention of the vaccine’s benefits to society appears to have no added value but also does not interfere with message concerning benefits to the child.