Missed, Refused Vaccines Appear in 'Clusters'
Clusters may deserve special outreach efforts, researchers say
MONDAY, Jan. 19, 2015 (HealthDay News) -- Parents who refuse to have their children vaccinated appear to be clustered in certain areas, a new study suggests. The report was published online Jan. 19 in Pediatrics.
Among 154,424 children in 13 counties in Northern California, the researchers found five clusters where children had missed one or more vaccinations by the time they were 3 years old. "It's known from other studies that areas where there are clusters of vaccine refusal are at higher risk of epidemics, such as whooping cough epidemics," lead investigator Tracy Lieu, M.D., M.P.H., a pediatrician and director of the division of research at Kaiser Permanente Northern California in Oakland, told HealthDay. "Clusters may deserve special outreach efforts to make sure parents have all the information they need to make informed decisions about vaccination."
Specifically, the researchers found the rate of missed vaccinations within these clusters ranged from 18 to 23 percent, compared with a rate of missed vaccinations outside the clusters of 11 percent. Missed vaccinations for measles, mumps, rubella, and varicella were similar in all the clusters, they added. In addition to missed vaccinations, children whose parents refused vaccinations were also found in clusters. In the clusters, vaccine refusal rates ranged from 5.5 to 13.5 percent, compared with 2.6 percent outside the clusters.
Parents who decline or delay vaccines do so for a variety of reasons, Lieu explained. "Many parents have questions about the safety of vaccines, and it's natural to have these concerns even though there's reassuring evidence available about many questions regarding vaccine safety," she said. "Sometimes parents decline vaccines they don't think are necessary; other studies have found this tends to happen with chickenpox vaccine, for example. Other times parents are concerned that vaccines might cause side effects."