What are the most appropriate preventative methods for a child showing signs and symptoms (S&S) of measles?

Post-Exposure Prophylaxis with MMR Vaccine

For a child showing signs and symptoms of measles, the most appropriate preventative method is post-exposure prophylaxis with MMR vaccine administered within 72 hours of initial exposure to prevent or modify disease in susceptible contacts, combined with immediate isolation of the symptomatic child and vaccination of all other susceptible household members and close contacts. 1

Immediate Management of the Symptomatic Child

The child with active measles symptoms should be immediately isolated and kept out of school or daycare for at least 4 days after rash onset, as patients are contagious from 4 days before rash to 4 days after rash appears. 2, 1

• Supportive care with vitamin A supplementation is critical: 200,000 IU orally on day 1 for children ≥12 months or 100,000 IU for children <12 months, as this reduces measles severity and mortality. 3
• Laboratory confirmation should be obtained through measles-specific IgM antibody testing during the first clinical encounter. 3

Post-Exposure Prophylaxis for Contacts

MMR Vaccine (Preferred for Most Contacts)

MMR vaccine is the preferred post-exposure prophylaxis and should be administered within 72 hours of initial measles exposure to susceptible household contacts aged ≥6 months who can receive the vaccine. 2, 1

• Vaccine effectiveness for post-exposure prophylaxis is 74% when given within this timeframe. 4
• Susceptible contacts include anyone without documentation of two doses of measles-containing vaccine after their first birthday or other acceptable evidence of immunity. 2
• Vaccinated persons may be readmitted to school immediately, while unvaccinated persons must be excluded for 21 days after rash onset in the last case. 2

Immune Globulin (For High-Risk Contacts)

For contacts who cannot receive MMR vaccine or were not vaccinated within 72 hours, immune globulin should be administered within 6 days of exposure:

• Standard dose: 0.25 mL/kg IM (maximum 15 mL) for immunocompetent persons. 2, 1
• Higher dose: 0.5 mL/kg IM (maximum 15 mL) for immunocompromised persons. 2, 1
• High-risk groups requiring IG include: infants <12 months, pregnant women, and immunocompromised persons. 2

School and Community Control Measures

All susceptible students, siblings, and school personnel in affected schools should receive MMR vaccination immediately during an outbreak. 2

• Persons without documentation of adequate vaccination (two doses separated by ≥28 days after first birthday) should be vaccinated or excluded from school for 21 days after the last case's rash onset. 2
• Revaccination should extend to unaffected schools in the same geographic area that may be at risk for measles transmission. 2

Why Monovalent Measles Vaccine Is Not the Answer

Monovalent measles vaccine is only preferred for infants aged 6-11 months during outbreaks, but MMR may be used if monovalent vaccine is not readily available. 2

• For children ≥12 months (the typical age for symptomatic measles cases), MMR vaccine is the standard and preferred formulation. 2, 1
• The two-dose MMR schedule addresses primary vaccine failure, which occurs in approximately 5% of recipients after a single dose. 1

Critical Pitfalls to Avoid

• Do not delay vaccination waiting for monovalent measles vaccine when MMR is available—time is critical for post-exposure prophylaxis effectiveness. 2
• Do not use immune globulin for outbreak control—it is reserved for individual high-risk contacts only. 2
• Do not assume one dose of vaccine provides adequate protection—approximately 5% of single-dose recipients experience primary vaccine failure. 2, 1
• School exclusion alone without vaccination is insufficient—aggressive vaccination of all susceptible contacts is the cornerstone of outbreak control. 2