Measles resurgence in US compounded by nonmedical vaccine exemptions

Thanks to a highly effective vaccination program in the United States, measles was declared eliminated in 2000. Since then, imported cases of measles have caused numerous outbreaks in vulnerable populations throughout the country, and experts warn that the disease could easily make a comeback if vaccination rates continue to drop.

By the end of April, more measles cases had been reported in the U.S. in 2019 than in any other year since 1994, with several large outbreaks underway.

“In the last decade, the rates of measles in this country have consistently tracked with communities of lower immunization rates,” Matthew Zahn, MD, chair of the Infectious Diseases Society of America’s Public Health Committee, told Infectious Disease News. “What we are seeing now is not a surprise, unfortunately, and it is typical for what we have seen for several years.”

The problem is compounded by nonmedical vaccine exemptions. Eighteen states currently allow them for personal or philosophical reasons.

“The battleground is those 18 states, and they’re mostly Western and some Midwestern states allowing nonmedical exemptions for personal or philosophical beliefs,” Peter J. Hotez, MD, PhD, professor of pediatrics and dean of the National School of Tropical Medicine at Baylor College of Medicine and co-director of the Center for Vaccine Development at Texas Children’s Hospital, told Infectious Disease News.

Even slight reductions in MMR vaccine coverage caused by vaccine hesitancy could result in a threefold increase in measles cases, according to research published in JAMA Pediatrics.

Infectious Disease News spoke with pediatric infectious disease, public health and legal experts to explore how nonmedical vaccine exemptions — particularly those for personal or philosophical beliefs — are damaging to public health, as well as efforts that are underway to make it more difficult for people to opt out.

‘The big problem’

According to the CDC, people should be exempt from immunizations based on their medical status. These include people who have had a life-threatening allergic reaction to a component of the vaccine; people living with HIV/AIDS or another disease that affects the immune system; people who are treated with drugs that affect the immune system; and people who have any kind of cancer, who are being treated for cancer with radiation or drugs or who have a blood disorder.

Hotez said only three states allow vaccine exemptions exclusively for medical reasons: California, Mississippi and West Virginia. Although the remaining 47 states allow religious exemptions, Hotez said this is not a serious problem because not many religions prohibit vaccination.

“The big problem that is occurring in the Pacific Northwest, the American Southwest and parts of the Midwest is that those are the states that allow nonmedical exemptions for personal or philosophical beliefs,” he said.

Paul A. Offit, MD, director of the Vaccine Education Center and attending physician at the Children’s Hospital of Philadelphia, said in an interview that opting out of vaccination is not just a personal choice, but a choice that greatly affects public health.

“If you choose not to get a vaccine, it affects not only you, but those with whom you come in contact,” he said.

In a study published in Open Forum Infectious Diseases,Saad B. Omer, MBBS, MPH, PhD, the William H. Foege Professor of Global Health at Emory University, and colleagues found that the rate of nonmedical exemptions in states that allow their citizens to refuse vaccination on philosophical and religious grounds was nearly two and a half times higher than in states that allow nonmedical exemptions for religious reasons only. A separate analysis published in JAMA demonstrated that 56.8% of measles cases after 2000 occurred in patients who had no history of vaccination against the disease, and 70.6% of those who were not vaccinated had exemptions for philosophical or religious reasons.

Zahn said policies allowing only medical exemptions for school entry demonstrate to the community that vaccination is an important issue. He added that strict vaccination requirements help to ensure that parents do not opt out simply because it is more convenient than taking their children to see a physician.

In 2012, California took the extra step of requiring health care providers to sign off on all nonmedical vaccine exemptions. This caused a 25% decline in exemptions between 2013 and 2016. In 2015, after a large multistate outbreak traced to two Disney theme parks resulted in 147 cases, California passed stricter legislation, allowing only medical exemptions for children who attend public and private schools, as well as day care centers.

“The Disneyland outbreak was driven by children who had not been vaccinated. Those are the people who got sick, and those kids infected other people,” Zahn said.

He explained that one crucial factor in containing the outbreak was the high immunization rates among adults in the households of infected children, acting as a buffer.

“In the coming years, the children who grew up in this era of vaccine hesitancy will become parents themselves,” he said. “If we have another similar outbreak to what we saw at Disneyland, I’m very concerned that the adults who would be exposed to these kids would then have a lower immunization rate, which would allow the virus to spread more wildly though a community.”

In their study, Omer and colleagues noted that most states have not gone as far as California to eliminate exemptions because evidence points to the success of curbing nonmedical exemptions by restricting them instead of completely eliminating them.

“Our study suggests that eliminating philosophical exemptions and making the exemption procedures more stringent may be useful policy approaches in states that are waiting to learn from the California experience of eliminating nonmedical exemptions or where such a policy approach is not politically feasible,” they wrote.

Anti-vaccine ‘hotspots’

In a study published in PLoS Medicine, Hotez and colleagues identified 12 “hotspots” in metropolitan areas throughout the U.S. where people are opting out of immunizations in greater numbers.

In areas with high rates of nonmedical vaccine exemptions, the researchers observed low rates of MMR vaccine coverage, leaving unvaccinated residents susceptible to disease if an outbreak were to occur. Outbreaks have been reported in five of these hotspots in 2019 so far, according to Hotez.

Some of the hotspots that were identified in the study by Hotez and colleagues included several counties in Oregon and Washington, which recently declared a state of emergency to contain a measles outbreak. The proclamation, announced in late January, freed up resources in state agencies to assist affected communities.

New York City also declared a state of emergency over a large measles outbreak involving hundreds of cases in Brooklyn and Queens, most involving members of the Orthodox Jewish community.

“When vaccine coverage starts to decline, like what we are seeing in Clark County, Washington, in Portland, and most recently in Oakland County [Michigan], measles tends to be the first breakthrough infection we see,” Hotez said. “Measles is one of the most highly transmissible viruses known.”

Offit described measles as “the canary in the coal mine,” being one of the first vaccine-preventable diseases to return when there is an erosion of herd immunity.

According to Danielle Koenig, the immunization health promotion supervisor at the Washington State Department of Health, the state currently requires immunization with hepatitis B, DTaP, polio, MMR and varicella vaccines upon kindergarten entry. She told Infectious Disease News that the number of nonmedical vaccine exemptions has fluctuated over time, but she acknowledged that the state’s exemption rate is more than twice the national average.

“It is concerning that we have so many unprotected kids in our schools,” she said.

Koenig said she is not just concerned with the number of children who have nonmedical vaccine exemptions, but the number of children who are currently labeled as out of compliance with their vaccines but still attend school.

“Those are kids who we just do not have paperwork for,” she said. “They might have had their vaccines or might have not, but they have not turned in proof of immunity or an exemption form. We work with schools to get out-of-compliance kids in order, so that way we have a better picture of how many kids are protected in schools.”

Koenig said that since the measles outbreak in Washington began, there has been a “significant uptick” in vaccination. This is indicative of parents’ concerns about the disease, she said, and many unvaccinated children and adults are now receiving doses of MMR.

In 2019 alone, six measles outbreaks have been reported to the CDC in New York state (Rockland County), New York City, Washington, Texas, Illinois and California. The CDC said these outbreaks have been linked to travelers who brought measles back from other countries where large measles outbreaks are ongoing.

A global problem

Comparatively speaking, Offit said the U.S. has done well preventing the spread of vaccine-preventable diseases. For example, measles is a much more significant problem in Europe.

“These countries have fairly significant rates of endemic measles,” Offit said. “They invariably have measles deaths every year. We have not really had measles deaths here in children whose parents have decided not to vaccinate, but maybe that’s what it will take. Maybe it will take enough children dying that we realize that not vaccinating a child shouldn’t be an option.”

Europe saw almost 83,000 cases of measles in 2018 — more than triple the amount reported in 2017 and 15 times as many cases as 2016, according to WHO. In 2017, coverage with the second dose of measles vaccine reached 90% in Europe, which was the highest level the region ever achieved, and coverage with the first dose was 95%. However, according to Zsuzsanna Jakab, PhD, WHO Regional Director for Europe, this was not enough to interrupt transmission.

“The picture for 2018 makes it clear that the current pace of progress in raising immunization rates will be insufficient to stop measles circulation,” she said in a news release. “While data indicate exceptionally high immunization coverage at the regional level, they also reflect a record number affected and killed by the disease. This means that gaps at the local level still offer an open door to the virus.”

Globally, the picture is not much better. An MMWR published in November 2018 by Dabbagh and colleagues showed that measles cases surged 31% worldwide in 2017, driven by gaps in vaccination coverage. However, the MMWR also noted that countries in all six WHO regions have set goals to eliminate measles by 2020. Between 2000 and 2017, the estimated uptake of the first dose of a measles-containing vaccine increased from 72% to 85%. This was followed by an 83% decrease in annual reported measles incidence. In addition, measles deaths decreased 80% during this time, with researchers estimating that 21.1 million deaths were averted.

The researchers cautioned that to meet these goals, global vaccine coverage with the first and second doses of measles-containing vaccine must improve worldwide. They wrote that an important component to improving vaccination coverage is a “political commitment” that could guarantee significant and sustained investments in global and regional measles elimination.

Vaccine legislation

Research published in the American Journal of Public Health placed a spotlight on the U.S.’s political commitment to reduce the number of vaccine exemptions. Neal D. Goldstein, PhD, MBI, and colleagues found that more than half of bills proposed by state legislators that concerned immunization would increase people’s access to nonmedical vaccine exemptions.

Each state is responsible for creating its own immunization laws, which tend to be “wildly different” according to Brian Dean Abramson, Esq, LLM, a vaccine law expert and author of Vaccine, Vaccination and Immunization Law.

“Some states have specific language as to what kinds of documentation are needed to support a religious exemption. Some of them just say that a parent has to provide a statement saying that they have religious objections,” Abramson told Infectious Disease News. “Philosophical exemptions are even further along this direction because there is no real test of whether someone genuinely has either a religious or philosophical objection. These exemptions, where they exist, they put the concept in a black box that really cannot be investigated.”

In their study, Goldstein and colleagues found that 175 bills regarding immunization were proposed between 2011 and 2017, and 53% were considered anti-vaccine in nature. Although only 13 bills were actually signed into law, and the bills that were passed were 91% less likely to be anti-vaccine, Goldstein expressed concern about the information legislators are using to make their decisions on public health matters.

“Public health and medical societies can be influences on legislators, so this study should act as an alarm that the majority of bills in state legislatures are anti-vaccination,” Goldstein told Infectious Disease News. “Even though the ones that make it to law are pro-vaccination, the fact that these anti-vaccination bills are even introduced is concerning. Organizations like the AAP have a specific role to play in ensuring that evidence-based bills are supported, and nonevidence-based bills are dismissed.”

For example, Goldstein said a representative in New Jersey believed she was introducing a bill that was evidence based. She emailed the study to Goldstein, who said it was a “flawed analysis linking hepatitis B vaccination with autism.”

It is unclear what it would take for states to universally accept the abolishment of vaccine exemptions for personal or philosophical beliefs. In 1984, Congress passed the National Minimum Drinking Age Act, which withheld 10% of federal highway funding from states that did not maintain a minimum legal drinking age of 21 years. Abramson explained that it would be impractical to expect any strong federal imposition like this regarding the issue of vaccine exemptions.

However, he said an effective strategy to improve vaccination rates among states is to persuade state legislators to individually adopt practices that will “reduce the number of exemption claims while at the same time increase awareness about the benefits of vaccination and the degree to which anti-vaccine arguments hinge on misconceptions.” One example is to require counseling from a health care provider before obtaining an exemption so that families have the necessary information before making their decision, much like the law California enacted in 2012.

“The big thing about the age we are living in is that misinformation can spread so much faster and gain so much more traction than it ever has been able to before,” Abramson said. “There is nothing that we can do about that legally. The First Amendment protects bad information just as readily as it protects good information.”

Promoting vaccination

Offit claims that “vaccines are a victim of their own success” — meaning that people are less likely to fear diseases they have never seen before, and this makes them more likely to risk their child’s health by opting out of immunization. This, he said, is “just a natural history of an immunization program.”

Zahn stressed that much of the conversation surrounding vaccination in the U.S. is driven by a small minority of the population who are strongly anti-vaccine. He said many people who are pro-vaccine are not often as passionate, or vocal, about the subject.

“Very often, for people who are pro-vaccine, the issue stops at making sure that they get their child vaccinated,” Zahn explained. “It has been a challenge to consistently generate pro-vaccine advocates on the state level. In all 50 states, there is a need to identify legislative champions and immunity champions to make sure that anti-vaccination legislation is not passed and to make sure that everybody understands the public health stakes involved.”

On the federal level, there appears to be little support to improve vaccine uptake. President Donald J. Trump has repeatedly aligned with anti-vaccine views and flirted with the idea of tapping Robert F. Kennedy Jr., a known vaccine skeptic, to chair a commission about vaccine safety. Kennedy pushed a widely discredited link between thimerosal-containing vaccines and autism. The British Medical Journal has also linked Trump to meetings with Andrew Wakefield, who published a fraudulent study linking MMR vaccination to autism. The study has been discredited and redacted, and Wakefield has had his medical license revoked.

Abramson noted that there has been some recent evidence that Trump has backed off his anti-vaccine position. Kennedy told The Guardian that “zero progress” was made regarding the commission, and the administration had “cut off all communication.”

Nevertheless, Hotez said the most important driver of the problem is the anti-vaccine lobby, which has been highly effective on the state level.

“State legislators have allowed themselves to be played,” he said.

Hotez and Offit agreed with Goldstein that medical societies have a role in influencing legislators to promote laws that are pro-vaccination. Specifically, Hotez said many organizations have been actively pushing back against misinformation, including the IDSA, the National Foundation for Infectious Diseases and the Pediatric Infectious Diseases Society. Offit added that Voices for Vaccines, Vaccinate Your Family and the Immunization Action Coalition also have pushed back against anti-vaccine rhetoric in state legislatures.

“I think that the anti-vaccine people see efforts by state legislators to make it more difficult to opt out of vaccines as their enemy, but that is not their enemy,” Offit said. “The outbreaks are their enemy, because the outbreaks are what turn public opinion against them. There is only one way to stop the outbreaks, and that is by vaccinating.”

Offit predicted that the anti-vaccine movement will not last because it is “not built on science. It is built on false fears.” In addition, he said the mainstream media are less inclined give equal weight to anti-vaccine viewpoints than they were 15 years ago.

Hotez framed the issue of vaccination as a human right for children, and he stressed that parents are violating that right when they choose not to vaccinate because they “read some piece of garbage” on a website.

“In my opinion, it is a fundamental right of childhood to be protected against deadly, serious or harmful infectious diseases,” Hotez said. “It is a human right of childhood just like it is a human right of childhood to be put in a car seat or wear a safety belt. We have laws for that. That is not a choice, that is the law, and I think it should be the same way for vaccinations.” – by Katherine Bortz

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• For more information:
• Brian Dean Abramson, Esq, LLM, can be reached at briandeanabramson@gmail.com.
• Peter J. Hotez, MD, PhD, can be reached at hotez@bcm.edu.
• Danielle Koenig can be reached at danielle.koenig@doh.wa.gov.
• Paul A. Offit, MD, can be reached at offit@email.chop.edu.
• Matthew Zahn, MD, can be reached at mzahn@ocha.com.

Disclosures: Abramson, Hotez, Koenig, Offit and Zahn report no relevant financial disclosures.