Parents who choose not to vaccinate their children can be held responsible for the recent surge in the measles and pertussis outbreaks that have been occurring in the U.S., according to a new study.
A team at Emory University examined previously published studies and reports on outbreaks, which included 18 on measles and 32 on pertussis, a highly contagious bacterial infection that causes whooping cough.
For measles, the researchers found that 57 percent of the 1,416 cases involved people between 2 weeks and 84 years old who were never vaccinated. Out of the 970 cases that had detailed data on the individual's vaccination history, the researchers found that 574 cases involved people who were eligible for the measles vaccine. Four-hundred five of these cases had cited non-medical reasons, such as religion.
The researchers reported that for pertussis, the rate of unvaccinated or under-vaccinated cases taken from the five largest statewide outbreaks ranged from 24 to 45 percent. In some of the outbreaks, however, the researchers found that many of the cases occurred in communities that had high vaccination rates, which suggested that the effectiveness of the vaccine could be waning. Overall, the researchers looked at 10,609 cases that occurred in people in the age range of 10 days to 87 years.
The researchers stressed that improving vaccination rates is vital for individual and community health. Study author Omer Saad, who is a pediatrics and epidemiology researcher at the university, said that outbreaks can be detrimental to the community because they increase risk of infection in children who have already been immunized.
"What this latest comprehensive review illustrates is that individuals who refuse vaccines not only put themselves at risk for disease," Matthew M. Davis from the University of Michigan said. "It turns out that they also put others at risk too - even people who have been vaccinated before, but whose protection from those vaccinations may not be as strong as it used to be."
Davis added in an accompanying editorial to this study, "The U.S. population wants vaccination to be safe, effective and available in a timely manner, and for immunization to be durable. Current challenges with measles and pertussis outbreaks provide an opportunity to develop and evaluate approaches to achieve unprecedented levels of vaccination coverage, limit waning immunity, and minimize vaccine-preventable disease for children and adults alike."
The study's findings were published in JAMA.
