- Han G, et al. MMWR Morb Mortal Wkly Rep.2019;68:201-202, http://bit.ly/2CFwhGK.
Measles is extremely contagious. Prior to development of the first vaccine in 1963, 90% of children were infected by 15 years of age.
Classic symptoms of measles include fever, cough, coryza, conjunctivitis, Koplik spots and maculopapular rash. The incubation period is seven to 10 days following exposure. Patients are most contagious four days before and four days after appearance of rash.
Of those infected, 30% experience complications, including diarrhea (8%), otitis media (7%), pneumonia (6%), seizures (0.7%), encephalitis (0.1%) and/or death (0.2%). Subacute sclerosing panencephalitis (SSPE), a progressive neurologic disorder, occurs in one in 25,000 patients, and more commonly affects patients younger than 2 years. There is no treatment for SSPE, and death usually occurs one to three years after diagnosis.
Rise of vaccine hesitancy
In 1998, The Lancet published a case series of 12 children using an uncontrolled study design. This flawed study suggested that measles-mumps-rubella (MMR) vaccine may predispose to behavioral regression and developmental disorder.
Due to the publicity the study received, parents became fearful of the unsupported linkage between the MMR vaccine and autism. Vaccination rates began to decline, and measles cases increased in the years following. Although the manuscript was retracted in 2010, vaccine hesitancy continues, despite lack of evidence linking MMR vaccine with autism.
California Senate Bill 277
Following several measles outbreaks, including an outbreak at Disneyland in 2015, California passed Senate Bill 277 (SB 277), which limited vaccine exemptions based on parental personal beliefs for children entering school. Unvaccinated children are permitted to attend private or public school, child care centers or nursey schools only if their parents filed a personal belief exemption form prior to Jan. 1, 2016, when the law took effect, or they obtain a medical exemption from a physician.
The first reported outbreak involving a patient with an exemption after passage of SB 277 was identified by the Santa Clara County Public Health Department (SCCPHD) on March 4, 2018 (see figure). Patient A, an unvaccinated 15-year-old male, recently returned from England and Wales, presenting with fever, cough, coryza, conjunctivitis, Koplik spots and rash. His immunocompromised brother, an organ transplant recipient, had gone on the same trip but received immunoglobulin prior to traveling overseas.
On return, patient A then infected unvaccinated patient B (at a scouting event), unvaccinated patient C (a classmate in quarantine) and unvaccinated patient F (at a tutoring center). Patient C’s 17-year-old sister received the MMR vaccine when her brother was quarantined and did not show signs of measles infection.
Patient F infected his unvaccinated brother (patient G) and his unvaccinated uncle (patient E). Patients F and G had received identical medical exemptions from all vaccines by a physician located several hundred miles away from the patients’ home.
Patient D, a 21-year-old who had received two doses of MMR vaccine, attended a different scouting event with patient B and presented with modified measles upon returning to college in Nevada. None of the vaccinated college contacts of patient D became infected with measles, indicating that vaccination reduced infectivity.
The SCCPHD and the Washoe County (Nevada) Health District expended a large amount of resources to quarantine and investigate this outbreak, highlighting the continued importance of stricter public health and legislative efforts to maintain high vaccination rates.
Vaccine recommendations and safety
The MMR vaccine is one of the most immunogenic vaccines available. Vaccination is 93% effective following the first dose and 97% effective after the second dose.
In the U.S., vaccination with MMR is recommended between 12-15 months of age and again at 4-6 years of age. The second dose was added to the vaccine schedule in 1988 following a spike in measles cases the year prior.
The vaccine may be given as young as 6 months of age during a community outbreak or if a patient is traveling to a measles-endemic area. Because infants may have maternal antibodies, which may blunt the immune response, patients still require two vaccinations at the recommended schedule.
If an unvaccinated patient is exposed to measles, the MMR vaccine may be given within 72 hours, or intravenous immunoglobulin may be given up to 96 hours as post-exposure prophylaxis.
To maintain herd protection against measles within a population, 95% of people must be vaccinated. If a low level of MMR vaccine uptake persists, the increasing number of unimmunized people will lead to an increase in the reproductive number (the mean number of secondary cases per infection) and possibly re-establishment of endemic measles and associated mortality.
Health care professionals who suspect that a patient has measles should keep the patient in airborne isolation during the infectious period. To test for measles, physicians should obtain reverse transcription polymerase chain reaction from the patient’s serum, a throat swab and urine sample. The local or state health department should be notified immediately to help identify and quarantine exposed contacts as soon as possible.
Comment
In their attempt to avoid the perceived risk associated with vaccination, vaccine-hesitant parents’ behavior collectively results in a significant increase in the real risk of measles exposure.
Pediatric health care providers are in a unique position to advocate for vaccination against preventable diseases both to patients and through legislation.
A recent prospective cohort study of 657,461 children in Denmark showed no association between the MMR vaccine and autism diagnoses (Hviid A, et al. Ann Intern Med. March 5, 2019), adding to the evidence supporting the safety of MMR vaccine.
Question
Hospitalized children with measles should be placed in isolation with standard precautions, including which of the following?
A. Hand hygiene
B. Gowns and gloves
C. Mask and eye protection
D. Environmental control
E. All of the above
Answer:E
Dr. Teherani is a post-graduate training fellow in pediatric infectious diseases at Emory University School of Medicine and Children’s Healthcare of Atlanta (CHOA). Dr. Pickering is adjunct professor of pediatrics at Emory University School of Medicine and CHOA.
