The local or state health department should be contacted immediately when sus- pected cases of measles occur in a community. All reports of suspected measles cases should be investigated promptly. Because of the potential for rapid spread of the dis- ease, one confirmed case of measles in a community is an urgent public health situation. Once a case is confirmed, prompt vaccination of susceptible persons at risk for exposure may help prevent dissemination of measles. Control activities should not be delayed pending the return of laboratory results from persons with suspected or probable cases. Persons who cannot readily provide acceptable evidence of measles immunity (Table 1) should be vaccinated or excluded from the setting of the outbreak (e.g., school, day care facility, hospital, clinic). Almost all persons who are excluded from an outbreak area because they lack acceptable evidence of immunity quickly comply with vaccination requirements. Persons exempted from measles vaccination for medical, religious, or other reasons should be excluded from involved institutions in the outbreak area until 21 days after the onset of rash in the last case of measles. Mass revaccination of entire communities generally is not necessary. Staff of the National Immunization Program, CDC, are available to assist health departments in developing an outbreak control strategy.
Measles Outbreaks Among Preschool-Aged Children
Although most infants are protected from measles by maternal antibody, the dis- ease is often more severe when it affects children aged <12 months. If cases are occurring among infants aged <12 months, measles vaccination of infants aged as young as 6 months may be undertaken as an outbreak control measure. Monovalent measles vaccine is preferred, but MMR vaccine may be administered if the monova- lent vaccine is not readily available (see Routine Vaccination—International Travel). Children vaccinated with measles or MMR vaccine before the first birthday should be revaccinated at age 12–15 months and again before entering school.
Passive immunization with IG may be preferred for infants aged <12 months who are household contacts of measles patients, both because it is likely they will have been exposed >72 hours before diagnosis of the disease in the household member and because they are at highest risk for complications from the disease (see Use of Vaccine and Immune Globulin Among Persons Exposed to Measles, Rubella, or Mumps). IG should not be used to control measles outbreaks.
Measles Outbreaks in Day Care Facilities, Schools, and Other Educational Institutions
During an outbreak in a day care facility, revaccination with MMR is recom- mended for all attendees and their siblings who have not received two doses of measles-containing vaccine on or after the first birthday and who do not have other evidence of measles immunity. Facility personnel (e.g., employees, volunteers, serv- ice providers) who cannot provide acceptable evidence of immunity (Table 1) also should be vaccinated with MMR. Revaccination also should be considered for unaf- fected child care facilities in the community that may be at risk for measles exposure and transmission.
During outbreaks in schools (elementary, middle, junior and senior high schools, colleges and other institutions of higher education), a program of revaccination with MMR vaccine is recommended in the involved schools. Revaccination of students and personnel of unaffected schools in the same geographic area who may be at risk for measles transmission also should be considered. Revaccination should include all stu- dents and their siblings and all school personnel born during or after 1957 who cannot provide documentation of adequate measles vaccination or other acceptable evidence of measles immunity. For persons born in 1957 or later, adequate vaccination consists of two doses of measles-containing vaccine separated by at least 28 days with the first dose administered no earlier than the first birthday (Table 1) ( see Documentation of Immunity). Persons who cannot readily provide documentation of acceptable evi- dence of measles immunity should be vaccinated or excluded from the day care facility, school, or other educational institution. Revaccinated persons, as well as per- sons who receive their first dose as part of the outbreak control program, may be readmitted to school immediately. Persons exempted from measles vaccination for medical, religious, or other reasons, and those who refuse vaccination for any reason, should be excluded from the day care facility, school, or other educational institution until 21 days after the onset of rash in the last case of measles.
Measles Outbreaks in Health-Care Settings
If a measles outbreak occurs within a health-care facility (e.g., hospital, clinic, phy- sician office) or in the areas served by the facility, all persons working at the facility
who cannot provide documentation of two doses of measles-containing vaccine sepa- rated by at least 28 days with the first dose administered on or after the first birthday, or who do not have other evidence of measles immunity (Table 1), should receive a dose of MMR vaccine. If indicated, health-care workers born during or after 1957 should receive a second dose of MMR vaccine at least 28 days after the previous dose (see Documentation of Immunity). Some health-care workers born before 1957 have acquired measles in health-care facilities and have transmitted the disease to patients or coworkers (see Health-care Facilities). Therefore, during outbreaks, health-care fa- cilities also should strongly consider recommending a dose of MMR vaccine to unvaccinated health-care workers born before 1957 who do not have serologic evi- dence of immunity or a history of measles disease.
Serologic testing of health-care workers before vaccination is not generally recom- mended during an outbreak because arresting measles transmission requires rapid vaccination of susceptible health-care workers. The need to screen, wait for results, and then contact and vaccinate susceptible persons can impede the rapid vaccination needed to curb the outbreak.
Susceptible health-care workers (Table 1) exposed to measles should receive a dose of MMR vaccine and should be removed from all patient contact and excluded from the facility from the fifth to the 21st day after the exposure. They may return to work on the 22nd day after exposure. However, susceptible health-care workers who are not vaccinated after exposure should be removed from all patient contact and excluded from the facility from the fifth day after their first exposure to the 21st day after the last exposure, even if they receive postexposure IG. Personnel who become ill with prodromal symptoms or rash should be removed from all patient contact and excluded immediately from the facility until 4 days after the onset of their rash.
Use of Quarantine
Imposing quarantine measures for outbreak control is usually both difficult and dis- ruptive to schools and other organizations. Under special circumstances (i.e., during outbreaks in schools attended by large numbers of persons who refuse vaccination), restriction of an event or other quarantine measures might be warranted (226). How- ever, such action is not recommended as a routine measure for control of most outbreaks.