On Tuesday, September 3, New York City officials declared an end to the measles outbreak in the Brooklyn neighborhood of Williamsburg, after 2 consecutive incubation periods with no new reported cases. Perhaps the largest and most notable measles outbreak during the ongoing epidemic facing the US over the past year, the successful containment of measles in New York City is good news and a testament to the hard work and dedication of health and elected officials, healthcare workers and health systems, and community partners. The outbreak lasted nearly a year and ended with more than 650 cases. Despite this high-profile success, measles outbreaks continue across the US—including in nearby Rockland County, New York—and in many other countries, so the threat is far from over.

This week’s Outbreak Thursday takes a closer look at some of the interventions used in New York’s effort to bring this outbreak under control and the resources required to implement them. We will also try to put this success in the context of the re-emergence of measles in the US and other countries.

A Successful Response

Ultimately, the New York City measles outbreak resulted in 654 total cases, including 52 hospitalizations and 16 admissions to intensive care units. Typically, about 1 in 5 measles patients in the US requires hospitalization, so the hospitalization rate in New York City was better than expected. Fortunately, there were no reported deaths associated with the outbreak, which can occur in approximately 1-3 out of every 1,000 cases. Notably, 80% (525) of the cases were in children under 18 years old. The outbreak largely affected the Orthodox Jewish community in Williamsburg, including transmission at schools and centers of worship serving this population, and the outbreak was exacerbated by low vaccination coverage in the community. Only 5% of cases were in individuals known to be fully vaccinated; 73% of cases were unvaccinated, 7% were partially vaccinated, and 15% did not know their vaccination status.

The outbreak response involved more than 500 personnel and cost more than $6 million. For those of you playing along at home, that’s more than $9,000 per case, not including the healthcare costs for affected individuals. ODA Health, a primary care network serving the Williamsburg community, administered more than 5,000 vaccinations over the course of the outbreak. The heath response included considerable public communication and education efforts as well, including pamphlets and advertisements published in English, Yiddish, and Spanish; town hall events; and robocalls to the public to promote recommended protective actions, including vaccination, and combat widespread misinformation surrounding the outbreak, particularly efforts aiming to foment anti-vaccine sentiment.

In addition to the direct response-related activities, city and state officials took a variety of measures to mitigate the measles risk. In February 2019, the city health department updated measles, mumps, and rubella (MMR) vaccination guidance for healthcare providers in the affected communities to include an accelerated MMR vaccination schedule. Specifically, the guidance recommended an “extra, early dose” of MMR vaccine for infants aged 6-11 months in the affected communities—in addition to the normal MMR schedule (ie, 1 dose at 12-15 months and a second dose at 4-6 years). Additionally, the guidance recommended that children aged 1-4 years in the affected communities receive their second dose of the MMR vaccine early, as long as it is administered more than 28 days after the first dose. In April 2019, New York City Mayor Bill de Blasio and Commissioner of Health Oxiris Barbot issued a public health emergency declaration for affected areas in Brooklyn, which mandated that all unvaccinated individuals living or working in these areas receive the MMR vaccine (or demonstrate immunity to measles), a provision ultimately upheld by the courts. The city also closed several schools for failing to comply with the order. The city’s efforts called additional attention to the severity of the growing outbreak (at the time, approximately 250 cases), particularly in light of the upcoming Passover holiday and the associated risk of further transmission, and aimed to increase immunity in the affected communities. At the time of the emergency declaration, Dr. Barbot decried the efforts of anti-vaccine groups to spread mis- and disinformation, which helped fuel continued transmission in affected communities.

The state of New York also eliminated religious exemptions for childhood vaccination requirements to enroll in school. With this legislation, New York became only the 5th state to eliminate all non-medical exemptions for vaccinations required for school enrollment—New York had previously eliminated personal belief/philosophical exemptions. Mississippi and West Virginia eliminated non-medical exemptions years ago, and Maine enacted its legislation in May 2019 (takes effect in 2021). California eliminated non-medical exemptions in 2015, and concern about an associated increase in medical exemptions in the years since prompted efforts to improve oversight of this process across the state. In an effort to prevent this very issue, New York health officials issued “emergency regulations” that outline specific conditions for which medical exemptions can be issued and require physicians to provide documentation of the applicable conditions for each exemption issued. Additionally, medical exemptions are required to be reissued annually rather than at designated points throughout the child’s schooling (eg, entry to specific grades).

The relationship between the government and the affected community in Williamsburg has a complex history, and many barriers likely existed at the onset of the outbreak that hindered full engagement with at-risk members of the public. But ultimately, partnerships built between health officials and community leaders and organizations, including local physicians and healthcare networks, have been described as critical to the success of promoting and implementing necessary public health interventions. The nature of these partnerships and the mechanisms by which they were established, strengthened, and utilized deserve their own dedicated analysis.

Rockland County

Similar efforts have been made in Rockland County, New York, in response to an ongoing measles outbreak there. In October 2018, the New York State Department of Health and Education Department notified administrators of affected schools that the Rockland County Health Commissioner was authorized to exclude unvaccinated students from school in response to the outbreak. Rockland County officials declared an emergency in March 2019, which barred unvaccinated individuals from public spaces, including “shopping centers, businesses, restaurants, schools, and places of worship.” This provision was struck down after legal challenge, and a subsequent emergency declaration was issued in April. The second emergency declaration included provisions for mandatory vaccination as well and provided access to emergency supplemental funding. The emergency continued until July 2019, but the outbreak is still ongoing (312 cases as of August 26). As of March 2019, more than 17,000 vaccinations had been administered in Rockland County since the beginning of the outbreak.

Continued Risk

As you can see, health officials made extraordinary efforts to contain the measles outbreak in New York City. The risk, however, is far from over. The outbreak in Rockland County continues, which poses continuing risk to surrounding jurisdictions. Additionally, both the outbreaks in New York City and Rockland County involved cases of the disease imported by travelers arriving or returning from overseas. Measles remains endemic in many countries, including Albania, the Czech Republic, Greece, and the UK, all of which recently had their measles elimination status rescinded by the WHO after prolonged measles transmission. As a result, there is always the risk of unvaccinated travelers bringing the disease to communities across the country. Notably, ongoing measles outbreaks in the US may put the country at risk of losing its measles elimination status as well, if they are not brought under control soon. In fact, the US has reported 1,234 measles cases in 31 states so far in 2019 (as of August 29)—the highest annual total since 1992 and nearly double the next highest total over the past decade (667 cases in 2014)—and there are 3 ongoing outbreaks, including 2 in New York.

Whether a result of domestic transmission or imported cases, the risk of measles and other vaccine-preventable diseases remains as long as there are pockets of low vaccination coverage, due to unvaccinated or undervaccinated individuals. Public health and healthcare professionals must remain vigilant for the emergence of measles and other communicable diseases in order to rapidly implement response operations before the disease can gain a foothold in the community. Once this happens, the resources, operations, and policies required to contain it escalate quickly.

Photo: Statue of Liberty, New York City. Courtesy of Pixabay.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.