What are the Australian guidelines for measles prevention, vaccination schedule, post‑exposure prophylaxis, isolation, and management?

Australian Measles Guidelines

Routine Vaccination Schedule

All Australian children should receive MMR vaccine at 12 months of age, with a second dose at 4 years (or 10-16 years for catch-up). 1, 2

• The standard vaccination age is 12-15 months for the first dose, based on Australian research showing 95% seroconversion rates at this age with no advantage to delaying until 15 months. 3
• The second dose was lowered from 10-16 years to 4 years of age following the 1998 Measles Control Campaign, which successfully interrupted indigenous transmission. 2
• Aboriginal children in central Australia receive their first dose at 9 months due to higher risk. 3
• Two documented doses of MMR constitute presumptive immunity, regardless of subsequent serologic testing results. 4

Post-Exposure Prophylaxis

Administer MMR vaccine within 72 hours of exposure to susceptible contacts, or intramuscular immunoglobulin within 6 days if vaccination is contraindicated. 1, 5

MMR Vaccine Post-Exposure

• Give MMR within 72 hours of exposure to prevent or modify disease in susceptible individuals. 1, 5
• Healthcare workers without documented immunity should receive their first MMR dose immediately after exposure. 1
• Even previously vaccinated individuals may benefit from post-exposure MMR due to ~1% vaccine failure rates. 4

Immunoglobulin Dosing

• Standard dose: 0.25 mL/kg intramuscularly (maximum 15 mL) within 6 days of exposure. 1, 5
• Pregnant women: 0.25 mL/kg (maximum 15 mL) within 6 days. 1
• Immunocompromised patients: 0.5 mL/kg (maximum 15 mL) regardless of vaccination status. 1
• Australian research suggests current dosing may be suboptimal for measles, with modeling indicating 17.5 IU/kg (assuming 75% bioavailability) or 25.5 IU/kg (assuming 50% bioavailability) would be more effective. 6
• When immunoglobulin is administered, monitor contacts for 28 days (rather than 21 days) due to prolonged incubation period. 1, 5

Isolation Requirements

Isolate all measles patients for at least 4 days after rash onset in negative-pressure rooms with airborne precautions. 1, 5

Isolation Duration and Timing

• Patients are contagious from 4 days before rash onset through 4 days after rash onset. 1, 5
• Maintain isolation for the full 4 days after rash appears, not just until symptoms improve. 5
• Healthcare workers with measles must be excluded from work until ≥4 days following rash onset. 1, 5

Environmental Controls

• Place patients in negative-pressure airborne isolation rooms whenever available. 1, 5
• If unavailable, use a private room with the door closed. 1, 5
• Patients should wear a medical mask immediately upon arrival to healthcare facilities. 5

Healthcare Worker Protection

• All staff entering the room must wear N95 respirators (or equivalent), regardless of immunity status, because regular surgical masks are insufficient for airborne transmission. 1, 5, 4
• Only immune personnel should provide direct patient care to minimize exposure risk. 1, 5
• Exposed healthcare workers without immunity must be excluded from work from day 5 through day 21 post-exposure. 1, 5

Clinical Management

All children with measles must receive vitamin A supplementation: 200,000 IU for children ≥12 months, 100,000 IU for children <12 months. 1

Vitamin A Supplementation Protocol

• Standard dose: 200,000 IU orally for patients ≥12 months (including adults); 100,000 IU for children <12 months. 1
• Give vitamin A if the patient has not received it in the previous month. 7, 1
• Complicated measles (pneumonia, otitis, croup, diarrhea with dehydration, neurological problems) requires a second dose on day 2. 7, 1
• Eye symptoms of vitamin A deficiency (xerosis, Bitot's spots, keratomalacia, corneal ulceration) require an extended schedule: 200,000 IU on day 1, day 2, and 1-4 weeks later (half doses for children <12 months). 7, 1
• Vitamin A is the only evidence-based intervention to reduce measles mortality and should never be omitted. 1

Supportive Care

• Monitor nutritional status and enroll malnourished children in feeding programs. 7, 1
• Treat complications with standard therapies: oral rehydration therapy for diarrhea and antibiotics for acute lower respiratory infection and bacterial superinfections. 7, 1
• Undernutrition, fever, respiratory infection, diarrhea, HIV infection, and active tuberculosis are not contraindications to measles vaccination—undernutrition is actually a strong indication. 7

Outbreak Control Measures

Accelerate immunization efforts during outbreaks rather than postponing them; do not isolate patients in emergency/refugee settings. 7

• Vaccination programs should never be stopped or postponed because of measles presence in the community. 7
• During outbreaks, lower the vaccination age from 9 months to 6 months for high-risk populations. 7
• Children vaccinated between 6-9 months must be revaccinated after reaching 9 months (or 1 month later if they were 8 months at first vaccination). 7
• In educational settings, exclude susceptible unvaccinated individuals until 21 days after rash onset in the last case. 5
• In healthcare facilities, exclude exposed susceptible workers from day 12 after first exposure through day 26 after last exposure. 5

Common Pitfalls to Avoid

• Failing to isolate during the pre-rash phase: Patients are already contagious 4 days before rash appears, when diagnosis is most difficult. 5
• Using surgical masks instead of N95 respirators: Measles is airborne and requires respiratory protection for all staff, even those with presumptive immunity. 1, 5, 4
• Omitting vitamin A supplementation: This is the only intervention proven to reduce measles mortality and must be given to all cases. 1
• Relying on negative serology in vaccinated individuals: Antibody titers wane over time without loss of immune memory; two documented MMR doses constitute immunity regardless of subsequent testing. 4
• Inadequate immunoglobulin dosing: Current Australian guidelines may underdose measles-naïve individuals, and declining antibody levels in younger blood donors may further reduce NHIG effectiveness. 6, 8