National Press Club

Why are vaccine-preventable diseases rising? Panel offers reasons at media briefing

September 4, 2014 | By Galen Tan |

A panel of experts on vaccination issues and the producers of an upcoming PBS NOVA documentary on vaccines lent perspectives to the growing trend of opting their children out of immunizations and challenges of communicating with the public on vaccinations at a Sept. 4 National Press Club media briefing.

The airing of the documentary, "Vaccines – Calling the Shots," slated for Wednesday, Sept. 10, at 9 p.m. on NOVA PBS, comes at a time when outbreaks of vaccine-preventable diseases are on the rise. Almost 600 confirmed cases of measles have been reported in the United States to date in 2014, the highest number of cases in 20 years, according to the Centers for Disease Control and Prevention.

Paul Offit, director of the Children's Hospital of Philadelphia's Vaccine Education Center, explained that such outbreaks result from parents choosing to delay or opt out of vaccinating their children. Lower public vaccination levels, he said, can compromise "herd immunity," which protects all members of a community by reducing disease transmission rates in a mostly vaccinated population.

According to Offit, the herd immunity threshold for a population for a highly contagious disease like measles is 95 percent. Thus, he said, even a small number of individuals opting out of immunizations can endanger the 500,000 people in the United States who are unable to be immunized, such as those with medical issues or the very young.

Travelers returning from countries where such diseases are still widespread can spark an outbreak among the unvaccinated, he added.

"When herd immunity starts to break down, what you see is exactly what you see now. The most contagious diseases come back first," Offit said.

Sonya Pemberton, producer and director of the PBS documentary, noted that despite the vocal anti-vaccination minority, vaccination is the norm for the American public, with only 1 percent of the population is completely unvaccinated. However, she said, most of the public does have concerns and questions about immunization that should be addressed in an open and respectful manner.

"When I stopped and actually listened to them [anti-vaccination critics], I would discover that most of them were not against vaccines. They just wanted to ask questions," Pemberton said.

Brian Zikmund-Fisher, a University of Michigan public health professor, attributed some of the resistance to vaccination to how parents today, compared to previous generations, are unlikely to have personal experience with vaccine-preventable diseases.

"Seventy years ago, every parent, every grandparent knew personally of cases of the kinds of diseases that we now prevent with vaccines," he said. "We didn't have to sell vaccines to them. They wanted vaccines because they didn't want their children to grow up in a world in which these diseases were the threat that they were."

Zikmund-Fisher also noted while vaccines are safe, some parents who fear their child may suffer an adverse reaction to vaccines are not convinced.

"From a public health standpoint, vaccines are one of the safest things that medicine has to offer," he said. "But on a personal level, that's different."

Speaking on his experience covering the 2012 pertussis outbreak in Maine, Joe Lawlor, a health reporter for the Portland Press Herald, highlighted that while the scientific debate regarding vaccine safety and effectiveness has been settled, public debate is still ongoing. Lawlor urged journalists to communicate science separately from public opinion when covering vaccination-related stories.

"They're having a debate that they believe to be scientific but it's not scientific. So you can't do the whole this side believes this and that side believes this and let the readers decide," he said. "You are doing a disservice to the readers if you approach it like that."