Sarah is a 1-year-old girl who is brought by her mother Natalie to the pediatrician for a well-child visit. Sarah lives in a small suburban community with her parents and 4-year-old sister. Both Sarah and her sister are unimmunized, which has become an increasing trend in their community. The pediatrician discusses vaccinations with Natalie, who expresses concerns about their safety based on information she read on the Internet and heard from other people.
The pediatrician tells Natalie about a measles outbreak in New York City that occurred in a setting similar to their own. Natalie asks the pediatrician about measles, a disease she has neither seen nor knows about beyond the measles, mumps, and rubella (MMR) vaccine.
Measles is an acute viral illness that starts with a prodromal phase of fever and at least one of the “three Cs” (cough, coryza, and conjunctivitis) and progresses to a characteristic rash. Cases usually resolve with supportive care but complications including pneumonia, otitis media, and encephalitis can develop. The disease is highly infectious and although incidence remains low in the United States through vaccination, small outbreaks have occurred from imported cases and transmission among unvaccinated people.
A recent report published in NEJM describes the epidemiology of a measles outbreak in New York City and details measures such as mandatory vaccination and school exclusion that were used to control the outbreak. This report is a reminder that preventable diseases can spread in vulnerable populations with significant health and economic consequences.
The following NEJM Journal Watch summary explains the study and results in more detail.
Paying the Price for Undervaccination in New York City
Mary E. Wilson, MD reviewing Zucker JR et al. N Engl J Med 2020 Mar 12
Imported measles started a large outbreak in an area where many children were unvaccinated due to religious exemptions — and interventions were costly and disruptive.
In 2018, an unvaccinated child returned home from Israel to New York City with measles. Other cases followed. The NYC Department of Health and Mental Hygiene (NYC DOHMH) investigated suspected cases as well as MMR vaccine uptake and intervened to control the outbreak. Between September 2018 and July 2019, 649 cases of outbreak-related measles were confirmed.
Median age of patients was 3 years (age range, 1 month–70 years). Among those with known vaccination history, 85.8% were unvaccinated. Complications included diarrhea, otitis media, and pneumonia. Among 49 (7.6%) hospitalized, 40.8% received intensive care. The majority (93.4%) were from the Orthodox Jewish community, primarily in the Williamsburg area of Brooklyn. About 40% acquired infection through community-wide transmission. Contact tracing identified >20,000 named contacts, including about 1000 infants. Contacts were managed with postexposure MMR, immune globulin, or home quarantine. Schools and childcare programs required proof of vaccination or measles immunity, and an emergency order expanded requirement of vaccination or proof of immunity for all persons living, working, or going to school in the most affected areas. Outbreak responses involved 559 NYC DOHMH staff; the estimated direct cost was $8.4 million. Interventions included a campaign to combat vaccine myths in affected communities.
Comment: Although measles was declared eliminated from the U.S. in 2000, imported cases continue to ignite outbreaks where pockets of undervaccinated children persist. The outbreak in New York City, which is especially vulnerable because of the regular influx of travelers from other countries, was the largest in the U.S. in almost 30 years. A targeted campaign by antivaccination groups resulted in large unvaccinated populations, especially in children 1 to 4 years old. The existence of the Citywide Immunization Registry, established in 1996, provided high-quality data critical to an effective response, which also included mandatory vaccination and exclusion from school.
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Ken is a 2019-2020 NEJM Editorial Fellow and a paediatrician working in the National Health Service of the United Kingdom. He graduated from Imperial College School of Medicine and is training in general paediatrics in London.