Measles Post‑Exposure Management Guidelines (CDC)

Immediate Assessment of Immunity

• Susceptible contacts ≥ 6 months old should receive MMR vaccine within 72 hours of exposure; if MMR is contraindicated or the 72‑hour window has passed, administer immune globulin (IG) within 6 days. [CDC] 1, 2
• Presumptive immunity is established by:
• Any exposed individual lacking documented immunity requires immediate intervention. [CDC] 1

Post‑Exposure Prophylaxis by Population

Immunocompetent, Non‑Pregnant Persons ≥ 12 months

• Give MMR vaccine within 72 hours of exposure to prevent or modify disease; if the 72‑hour window has passed, still administer MMR for future protection. [CDC] 2, 4, 1
• For household contacts who present > 72 hours but < 6 days after exposure and have not received MMR, consider IG 0.25 mL/kg IM (max 15 mL); this is generally not recommended for non‑household immunocompetent contacts ≥ 12 months. [CDC] 2, 4

Infants 6–12 months

• Administer MMR within 72 hours of exposure (acceptable for household contacts ≥ 6 months). [CDC] 2
• Infants vaccinated before 12 months must receive two additional MMR doses starting at ≥ 1 year of age, spaced ≥ 28 days apart. [CDC] 2

Infants < 6 months

• Generally protected by maternal antibodies; no routine prophylaxis required unless maternal immunity is absent. [CDC] 2

Pregnant Women

• Provide IG 0.25 mL/kg IM (max 15 mL) within 6 days of exposure; MMR vaccine is contraindicated. [CDC] 2, 4, 5

Immunocompromised Persons

• Administer IG 0.5 mL/kg IM (max 15 mL) within 6 days of exposure regardless of vaccination status; IV IG 400 mg/kg may be used if IM volume is problematic. MMR vaccine is contraindicated. [CDC] 2, 4, 5
• Patients already receiving regular IGIV should have received 100–400 mg/kg within 3 weeks before exposure; if exposure occurs > 3 weeks after the last IGIV dose, consider an additional IG dose. [CDC] 5

Exclusion, Quarantine, and Monitoring

Healthcare Personnel

• Those vaccinated post‑exposure must be excluded from work days 5–21 after exposure. [CDC] 3, 1
• Those not vaccinated post‑exposure (even if given IG) must be excluded from all patient contact days 5–21 after the first exposure through day 21 after the last exposure. [CDC] 3, 1
• Personnel with only one documented MMR dose may continue working but must receive the second dose immediately. [CDC] 3, 1

Non‑Healthcare Contacts

• Quarantine until 21 days after exposure if there is no evidence of immunity and the individual has not received MMR or IG. [CDC] 3, 1, 2
• If IG was administered, extend monitoring to 28 days because IG can prolong the incubation period. [CDC] 1, 2

Infection‑Control Measures

• All healthcare workers caring for measles patients must wear N95 respirators regardless of immunity status (vaccine failure occurs in ~1 % of vaccinated individuals). [CDC] 3, 1
• Measles patients are contagious from 4 days before rash onset through 4 days after rash onset; maintain isolation for the full 4 days after rash appearance. [CDC] 3, 1

Common Pitfalls to Avoid

• Do not wait for serology after exposure; act immediately based on vaccination documentation. [CDC] 3, 1
• Do not assume persons born before 1957 are universally immune; consider vaccination in healthcare settings or outbreaks. [CDC] 3
• Use the higher IG dose (0.5 mL/kg) for immunocompromised patients and infants < 6 months; the standard 0.25 mL/kg dose is insufficient for these groups. [CDC] 2, 4
• Do not consider MMR given after 72 hours as useless; it still provides future protection. [CDC] 1, 2
• Symptomatic healthcare workers must remain excluded until at least 4 days after rash onset, not merely until day 21. [CDC] 3, 1