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Notes from the Field: Measles in a Patient with Presumed Immunity — Los Angeles County, 2015

Amanda Kamali, MD1,2; Chhandasi P. Bagchi, MPH3; Emmanuel Mendoza, MPH3; Dulmini Wilson, MPH3; Benjamin Schwartz, MD2; Laurene Mascola, MD2

On February 14, 2015, patient A, aged 17 years, was seen in an emergency department for evaluation of reactive airway disease. In the waiting room at the same time were two siblings, aged 6 months, presenting with fever and rash; these two children (patients B and C) were later confirmed to have measles. Patient A began a 5-day course of oral prednisone (50 mg per day); however, symptoms continued, and patient A returned to the emergency department the next day and received 125 mg of intravenous (IV) methylprednisolone. Patient A had documentation of receipt of 2 doses of measles, mumps, and rubella (MMR) vaccine at ages 12 months and 4 years.

A contact investigation was initiated by the hospital to identify all persons who might have been exposed to patient B or patient C. An infant aged 10 days was identified within the first 6 days of exposure and offered postexposure prophylaxis with intramuscular (IM) immune globulin. A second infant was identified later and was outside of the window period for immune globulin. Patient A was not identified as a susceptible contact in the investigation because of the documented history of receipt of MMR vaccine. Patients B and C had returned to the hospital on February 17, before receiving a diagnosis of measles, and exposed three other susceptible children (two infants aged <12 months and a child aged 3 years with leukemia). One infant was offered MMR vaccine, the other IM immune globulin, and the child with leukemia was offered IV immune globulin. On March 2, 16 days after the first emergency department visit, patient A was hospitalized for vomiting and dehydration. Patient A was also found to be febrile and to have a confluent papular rash that began on the face and spread to trunk and extremities and had small vesicular oral lesions. Measles was confirmed by laboratory testing, and patient A received supportive treatment with anti-emetics and IV fluids.

Patients A, B, and C were part of a measles outbreak originating at the Disney theme park in Orange County, California, in December 2014, which included 28 confirmed cases in Los Angeles County (1). As of April 17, 2015, a total of 136 measles cases had been documented in California, and among those, 10 patients had received at least 1 dose of MMR vaccine, 13 had received 2 doses, and two had received 3 doses (1; Jennifer Zipprich, PhD, Kathleen Harriman, PhD, California Department of Public Health, personal communication, June 2015). Measles is highly contagious, and high levels of population immunity are required to prevent transmission to susceptible persons. MMR vaccine is highly effective, with a single dose conferring immunity in 92%–95% of persons (2); however, because vaccine failures do occur, a second dose of measles vaccine has been routinely recommended since 1989 (3). Complications associated with measles include pneumonia, otitis media, diarrhea, and encephalitis; postexposure prophylaxis is recommended for all susceptible contacts (2,4). MMR vaccine, if administered within 72 hours of initial measles exposure, might provide some protection or modify the clinical course of disease. Persons who are at risk for severe illness and complications from measles who cannot receive MMR vaccine, including infants aged <12 months, persons who are severely immunocompromised (including persons taking high-dose steroids for ≥2 weeks), and persons with leukemia or lymphoma (2,5), should receive prophylaxis with immunoglobulin within 6 days of exposure.

Patient A had received 2 doses of MMR vaccine and did not meet criteria for being severely immunocompromised, however, this patient did develop measles after being exposed in the setting of a hospital emergency department to patients with laboratory-confirmed measles. Although it is not known whether patient A developed immunity to measles in response to the 2 administered doses of MMR vaccine, or whether patient A had an unrecognized immunocompromising condition, the recent steroid use might have weakened the patient's immune response and rendered patient A susceptible to wild measles strain. The diagnosis of measles in patient A highlights the concern that immunocompromised and susceptible persons might be exposed in a health care setting. More information is needed concerning the effect of immunomodulating drugs on vaccine-induced immunity to measles and other vaccine-preventable diseases.

1Epidemic Intelligence Service, CDC; 2Acute Communicable Disease Control, Los Angeles County Department of Public Health; 3Immunization Program, Los Angeles County Department of Public Health.

Corresponding author: Amanda Kamali,, 213-240-7941.


  1. California Department of Public Health. Surveillance update. Available at
  2. CDC. Prevention of measles, rubella, congenital rubella syndrome, and mumps, 2013: summary recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2013;62(No. RR-4).
  3. Rosen JB, Rota JS, Hickman CJ, et al. Outbreak of measles among persons with prior evidence of immunity, New York City, 2011. Clin Infect Dis 2014;58:1205–10.
  4. Perry RT, Halsey NA. The clinical significance of measles: a review. J Infect Dis 2004;189(Suppl 1):S4–16.
  5. California Department of Public Health. Measles investigation quicksheet. Available at

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