For employee health professionals, discovery of an undiagnosed measles case sitting in the ED typically sets off a mad scramble to track exposures and ensure healthcare worker immunity.

The antivaccine movement has greatly aggravated this situation, but the tide of public opinion may be turning.

As a record number of measles cases have spread to 30 states, science is starting to win the “vaccine wars,” said Paul Offit, MD, director of the Vaccine Education Center and an infectious disease physician at Children’s Hospital of Philadelphia.

“Frankly, it is hard to make a case that vaccines are evil in the midst of epidemics,” he said recently in Philadelphia at the annual meeting of the Association for Professionals in Infection Control and Epidemiology (APIC).

As of Aug. 29, 2019, there have been 1,234 measles cases this year in the United States, the CDC reports.1 That is the most cases since 1992, and makes a distant memory of the announcement in 2000 that measles had been eradicated in the United States — an accomplishment that was primarily due to childhood vaccinations.

Measles resurgence coincides with parents citing unsafe vaccines in declining to have their children immunized. However, there is a growing pushback against the antivaccine movement, with herd immunity threatened and the real risk of measles to immunocompromised patients and those who cannot receive immunizations.

“These outbreaks — as awful as they are, as children have once again suffered a disease that is completely preventable — we are reaping some good from this,” Offit said. “Society is finally standing up for itself.”

In addition to several states acting to remove exemptions to childhood vaccines, there has been an accumulation of studies thoroughly debunking the claim that the measles, mumps, rubella (MMR) vaccine causes autism. One of the most recent studies was published this year, with researchers who examined 650,000 children in Denmark concluding that there is no link between vaccination and autism.2

“When you isolate the effect of that one variable — receipt of the MMR vaccine — there was no greater risk of developing autism if you got the vaccine or if you did not,” Offit said. “There are 18 studies now that have looked at that hypothesis. I would argue that this is one of the most tested hypotheses in the history of medicine. MMR vaccine does not cause autism.”

Thimerosal Bungle

At times, public health attempts to accommodate and reassure those concerned about vaccines have been poorly handled, Offit said. For example, in the 1990s, attention turned to thimerosal, a preservative primarily used to prevent bacterial and fungal contamination of multidose vials of vaccine. To err on the side of caution, public health officials urged manufacturers to remove thimerosal from vaccines, even though it posed no established threat, said Offit, who was on the CDC’s Advisory Committee on Immunization Practices (ACIP) at the time.

“This was done the wrong way,” he said. “We removed thimerosal in a precipitous and frightening manner.”

The CDC announcement of the move said there was no evidence the mercury levels in thimerosal in vaccines were harmful. Pharmaceutical companies were urged to remove it “to make safe vaccines even safer,” he noted.

“If it is not unsafe, then taking it out doesn’t make it safe,” Offit said. “It only makes it perceived to be safe, which is a very different thing. We scared people the way that we did this. We somehow felt that a tenet of risk communication was the compulsion to describe all theoretical risk, and it was done wrongly. In any case, because that was done, it really gave birth to several antivaccine groups.”

Hospital Employee Health asked another national vaccine expert and longtime member of ACIP to weigh in on the thimerosal decision. “It continues to be debated as to how wise or unwise that decision was,” says William Schaffner, MD, professor of preventive medicine at Vanderbilt University.

The antivaccine movement saw the move in part as some kind of a concession, saying “they wouldn’t have done that unless there was a reason for it,” Schaffner recalls.

“The reason for it was to provide some calm,” he said. “[With the thinking being] we will henceforth make single doses without preservatives and that should keep everybody happy, even though it wasn’t a problem before. I think that remains an unresolved conundrum.”

While the science now is undisputed in the medical community regarding the MMR vaccine and autism, many in the antivaccine movement likely will hold to their beliefs and suspicions, he added.

“There has been a certain turnaround in public sentiment, but it’s not as though this group of people involved has suddenly changed their minds and every parent is bringing in their unimmunized children,” Schaffner said. “I think there will continue to be people who wish to exercise their ‘freedom’ or options and withhold their children from vaccination, science be darned.”

After a widely publicized measles outbreak at Disneyland, California passed a law in 2015 eliminating personal or philosophical beliefs as an exemption to childhood vaccinations for school attendance. With West Virginia and Mississippi, that resulted in three states with medical exemptions only. Several other states are considering or in the process of taking similar action to close loopholes to childhood immunizations.

“This is really dramatically different from where we were in the early 1980s,” Offit said.


  1. The Centers for Disease Control and Prevention. Measles cases and outbreaks. Available at: Accessed Sept. 3, 2019.
  2. Hviid A, Hansen JV, Frisch M, et al. Measles, mumps, rubella vaccination and autism: A nationwide cohort study. Ann Intern Med 2019;170:513-520.