Measles: Back again
ABSTRACT
Despite widespread vaccination against measles in the United States, outbreaks continue to occur. Clinicians should be able to recognize its distinctive clinical picture so that isolation measures can be instituted promptly, susceptible contacts immunized, and public health agencies notified. Vaccination is safe for most people and should be strongly promoted for all healthy children.
KEY POINTS
- Patients with measles are usually very sick with high fever, cough, rhinitis, and conjunctivitis.
- Koplik spots—small bluish-white lesions on the buccal mucosa—are usually evident only in the first few days of illness. Soon after, a patchy red rash develops, starting with the face and neck, then spreading to the entire body.
- Measles can lead to pneumonia, encephalitis, brain damage, and death.
- Suspected cases should be isolated and susceptible contacts vaccinated or given immunoglobulin if at high risk of developing severe disease.
- The diagnosis should be confirmed by serologic testing with measles-specific immunoglobulin M antibody.
- Vaccination confers lifelong immunity and is recommended for all healthy children in two doses: the first at 12 to 15 months of age and the second at the time of school entry.
VACCINATION RECOMMENDATIONS
The only measles vaccine available in the United States is a live further-attenuated strain prepared in chick embryo cell culture and combined with mumps and rubella vaccine (MMR) or with measles, mumps, rubella, and varicella vaccine (MMRV).
Healthy children. Two doses of measles vaccine are recommended, as a single dose is associated with a 5% failure rate. The recommended schedule is:
- First dose at age 12 to 15 months
- Second dose at the time of school entry (ages 4 to 6), or at any time at least 28 days after the first dose.19
More than 99% of children who receive two doses of vaccine according to this schedule develop serologic evidence of measles immunity. Vaccination provides long-term immunity, and many epidemiologic studies have documented that waning immunity after vaccination occurs only very rarely.21
All school-age children, including elementary, middle, and high school students, who received only one dose of measles vaccine should receive the second dose.
Adults born in 1957 or later should receive at least one dose of measles vaccine unless they have other acceptable evidence of immunity, such as:4
- Documentation of age-appropriate live measles vaccine, ie, one dose of vaccine for adults not at high risk, or two doses for those at high risk (see below)
- Laboratory evidence of immunity (ie, measles immunoglobulin G in serum)
- Laboratory confirmation of disease.
Adults born before 1957 can be considered to be immune to measles, although MMR vaccine can be administered in those without contraindications.
Adults at increased risk of exposure or transmission of measles and who do not have evidence of immunity should receive two doses of MMR vaccine, given at least 28 days apart. This high-risk group includes:
- Students attending college or other post-high school educational institution
- Healthcare personnel
- International travelers.
During measles outbreaks, every effort should be made to ensure that those at high risk are vaccinated with two doses of MMR or have other acceptable evidence of immunity.
LIVE VACCINE IS SAFE FOR MOST PEOPLE
Mild side effects. A transient fever, which may be accompanied by a discrete or confluent rash, occurs in 5% to 15% of recipients 5 to 12 days after vaccination.
Transmission does not occur. People who have been newly vaccinated do not transmit the virus to susceptible contacts, even if they develop a vaccine-associated rash. The vaccine can safely be given to close contacts of immunocompromised and other susceptible people.
Egg allergy not a concern. Measles vaccine is produced in chick embryo cell culture but has been shown to be safe for people with egg allergy and is recommended without the need for egg allergy testing.19
Autism link debunked. No scientific evidence shows that the risk of autism is higher in children who receive MMR vaccine than in those who do not. In 2001, an Institute of Medicine report rejected a causal relationship between MMR vaccine and autism spectrum disorders.22
CONTRAINDICATIONS
Measles vaccine is contraindicated for:
- Patients who have cell-mediated immune deficiencies, except human immunodeficiency virus (HIV) infection
- Pregnant women
- Those who have had a severe allergic reaction to a vaccine component in the past
- Those with moderate or severe acute illness
- Those who have recently received immunoglobulin products.
People with HIV infection who are severely immunosuppressed should not receive live measles vaccine. However, because of the risk of severe measles in HIV-infected patients and because the vaccine has been shown to be safe for patients with HIV without severe immunosuppression, the vaccine is recommended for those with asymptomatic or mildly symptomatic HIV infection who do not have evidence of severe immunosuppression (ie, CD4 lymphocytes < 15% or < 200 cells/µL).3,4
INFECTION CONTROL AND PREVENTION
Healthcare workers should maintain a high index of suspicion for measles and implement isolation procedures promptly in patients with a febrile illness, rash, and a history of travel abroad or contact with travelers from abroad.23 Suspected cases should be reported promptly to local health agencies to help limit spread.
Patients with measles should be placed in airborne isolation (eg, use of an N95 or higher level respirator and an airborne infection isolation room) for 4 days after the onset of the rash in a normal host and for the duration of the illness in an immunocompromised patient. Healthcare staff, regardless of their immunity status, should adhere to these precautions when entering the room of infected patients.
Immunization programs should be established to ensure that everyone who works or volunteers in healthcare facilities is protected against measles.4
Postexposure prophylaxis. Measles vaccination given to susceptible contacts within 72 hours of exposure may provide protection against infection and induces protection against subsequent measles exposures.24,25
Vaccination is the best intervention for susceptible contacts older than 12 months who do not have a contraindication to measles vaccination, and for those who have received only one dose of measles vaccine.
Passive immunization. Active immunization is the best strategy for controlling measles outbreaks. Passive immunization with intramuscularly or intravenously administered immunoglobulin given within 6 days of exposure can be used to prevent transmission or modify the clinical course of infection for susceptible contacts at high risk of developing severe or fatal measles. This includes people who are being treated with immunosuppressive agents, HIV-infected, pregnant, or younger than 1 year of age.
