Consistent advocacy needed to thwart resurgence: Measles over 3 decades
To mark our 30th anniversary, Infectious Diseases in Children will be examining some of the chronic conditions and infectious diseases that have impacted pediatric care over the past 3 decades.
Between 1987 and 1988, the number of measles cases reported to the CDC decreased by 7%, from 3,652 cases in 1987 to 3,411 in 1988. However, in 1989, the downward trend abruptly reversed, when 17,850 cases of the disease were reported, represented a 423% increase in the number of cases between 1988 and 1989.
The number of cases reported to the CDC reached 27,672 the following year. By that time, measles had been observed in 49 states as well as the District of Columbia.
“The measles epidemic of 1989 to 1991 in the United States resulted in tens of thousands of cases of the disease and hundreds of deaths,” Paul A. Gastañaduy, MD, MPH, of the division of viral diseases at the CDC, said in an interview. “Outbreaks in 1989 among school-aged children vaccinated with one dose of the [measles-mumps-rubella (MMR)] vaccine prompted the AAP and the Advisory Committee on Immunization Practices to recommend a second dose of the vaccine for all children.”
The two-dose vaccination schedule was implemented in 1989 and was intended, primarily, to induce immunity among children who did not obtain complete protection after the first dose, which was thought to be the main cause of the outbreak in the late 1980s and early 1990s. That outbreak was also partially responsible for the creation of the Vaccines for Children Program, which aimed to ensure that inability to pay did not prevent eligible children from receiving vaccines. The program took effect in 1994.
Together, these efforts decreased the number of reported measles cases in the United States in 1995 to 309. In 1998 and 1999, a record-low number of cases — 100 for both years — were reported to the CDC, and measles was declared eliminated from the U.S. in 2000.
“The elimination of measles from the U.S. was the result of high measles vaccination coverage in the United States, as well as better measles control in the Americas region,” Gastañaduy said. “In 2016, the Pan American Health Organization declared the Americas to be free of endemic measles. However, measles will continue to be a threat to the United States as long as it remains endemic in other areas of the world.”
Currently, the Americas is the only WHO region to have been declared free of endemic measles, although several ever-present national and international threats have the potential to derail this achievement. Inconsistent vaccination policies and lack of access are two of the primary causes of measles outbreaks outside the U.S.; individuals infected abroad who return home or travel to the U.S. can spread the disease within the country. In the U.S., inconsistent adherence to the vaccination schedule is still due, in large part, to ongoing concerns about the link between the MMR vaccine and autism.
“In the last decade, the main obstacle to vaccination has been an institution of claims that have been proven to be totally false,” Samuel L. Katz, MD, Wilburt C. Davison Professor Emeritus of Pediatrics at Duke University School of Medicine, told Infectious Diseases in Children. “The most serious of these claims occurred back in the late 1990s, when it was suggested that the measles vaccine causes autism.”
Anti-vaccine movement, presence of measles worldwide
In the February 1998 issue of The Lancet, Andrew Wakefield and colleagues published a paper that claimed to demonstrate a link between the MMR vaccine and autism. In the nearly 20 years since the paper was published, it has been formally retracted from The Lancet and numerous studies have refuted the supposed link between receipt of the MMR vaccine and the onset of autism.
“It took some time to disprove, but it was disproven over and over again in numerous studies,” Katz said. “However, the suspicion was enough to make parents concerned. Now, we have some young parents who haven’t seen measles and who are uncertain about whether the vaccines–autism link is true. But they certainly know what autism is, better than they know what measles is, and they want to avoid autism.”
Parents’ lingering concerns about the link between the MMR vaccine and autism in the United States are compounded by the absence of measles in the country, which lessens the perceived severity of the illness and may contribute to inadequate vaccination coverage.
“The reason parents make the choice not to vaccinate their children is because they don’t fear measles anymore. It’s not just that we have largely eliminated the disease; we have largely eliminated the memory of the disease,” Paul A. Offit, MD, director of the Vaccine Education Center at CHOP and an Infectious Diseases in Children Editorial Board member, said in an interview. “But the disease has come back to the United States, in the form of outbreaks in 2014 and 2015, in large part because parents chose not to vaccinate their children.”
The 2014 outbreak was concentrated in an Amish community in Ohio. The patients identified as the source of the outbreak appear to have contracted the disease during a trip to the Philippines; upon their return, the disease spread throughout their community, which included many individuals who had not been vaccinated. The 2015 outbreak occurred among 125 U.S. residents; 110 of these patients were residents of California, and about a third of them had visited one or both Disney theme parks in Orange County, California. The source of that outbreak was not formally identified, although specimens from a portion of patients demonstrate that the measles virus type in the outbreak was identical to the virus type responsible for an outbreak in the Philippines in 2014.
The source of these outbreaks underscores the potential for measles transmission in the United States stemming from unvaccinated individuals who travel to regions where measles is still endemic. As of April 2017, the CDC had issued a Level 1 travel alert for Belgium, Germany, Guinea, Italy, Indonesia and Romania due to measles outbreaks; the alert advises individuals traveling to those regions to ensure that their vaccines are up to date.
‘Nothing educates like the virus’
“The elimination of a vaccine-preventable infectious disease requires adequate vaccine delivery infrastructure, effective policies that promote high vaccination coverage, high-quality surveillance systems and coordinated efforts between countries,” Gastañaduy said. “The commitment made by the Ministries of Health of the countries in the Americas to control measles, and application of evidence-based strategies to reduce the measles disease burden, ultimately culminated in the elimination of measles in this region, and could serve as an example to other countries working toward this achievement.”
High levels of vaccine coverage, coupled with rapid responses to outbreaks by public health groups, are “critical” to prevent the disease from re-establishing itself in the country, according to the CDC.
“We do a pretty good job making sure that most children are vaccinated against measles,” Offit said. “Unfortunately, though, nothing educates like the virus. After the Disney outbreak in southern California, all these parents who were so confident that their child didn’t need the vaccine were suddenly running to the doctor for the vaccine because measles was knocking at their door and they were scared. You can try to use reason and explain to people why it is important to get a vaccine, but frankly, nothing educates better than fear.”
Emphasizing the disease’s severity for younger physicians and families who may have never seen a case of measles may be one of the most effective strategies for increasing uptake of the vaccine and maintaining control.
“The strength with which young doctors may try to convince parents go ahead with their immunizations is not as powerful as it was with physicians who spent their early years treating measles, measles encephalitis and measles pneumonia,” Katz said. “If we could deliver presentations with the sound of children coughing inexorably from measles, it might be a better way to convince them to vaccinate instead of listening to their doctor talk to them about a disease they know nothing about.”
“Young doctors didn’t grow up with these diseases and they don’t see them today,” he said. “They become far less powerful advocates for vaccines compared with older physicians. But vaccines aren’t a belief system. They stand on a mountain of evidence. Young doctors have to challenge people who choose not to vaccinate, because they are the child’s advocate.” – by Julia Ernst, MS, and Ryan McDonald
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Disclosures: Gastañaduy is employed by the CDC. Katz and Offit report no relevant financial disclosures.