From the Guidelines
Post-exposure prophylaxis (PEP) for measles should be administered as soon as possible, with the measles-mumps-rubella (MMR) vaccine given within 72 hours of exposure for most non-immune individuals, and immune globulin (IG) given within 6 days of exposure for those who cannot receive the vaccine, such as pregnant women, immunocompromised individuals, and infants under 6 months. The MMR vaccine is the preferred method of PEP for measles, as it can prevent or modify the disease course if administered within 72 hours of exposure 1. For those who cannot receive the vaccine, IG should be administered at a dose of 0.5 mL/kg intramuscularly (maximum dose 15 mL) for immunocompromised individuals, and 0.25 mL/kg (maximum dose 15 mL) for non-immunocompromised individuals 1. Key considerations for PEP include:
- The timing of administration, with earlier administration offering better protection
- The characteristics of the exposed individual, such as age, immune status, and pregnancy status
- The use of isolation measures to prevent further transmission, especially in healthcare settings where vulnerable populations may be present Some important points to note are:
- IG should not be used to control measles outbreaks 1
- The recommended dose of IG may vary depending on the individual's immune status and other factors 1
- Healthcare providers should consider the incubation period of 7-21 days when implementing isolation measures 1
From the Research
Post-Exposure Prophylaxis for Measles
- The National Advisory Committee on Immunization (NACI) recommends that susceptible immunocompetent individuals six months of age and older, who are exposed to measles and have no contraindications, be given measles-mumps-rubella (MMR) vaccine within 72 hours of the exposure 2.
- For susceptible infants younger than six months of age, intramuscular immunoglobulin (IMIg) should be provided at a concentration of 0.5 mL/kg, to a maximum dose of 15 mL administered over multiple injection sites, if injection volume is not a major concern 2.
- Susceptible infants six to 12 months old who are identified after 72 hours and within six days of measles exposure should receive IMIg (0.5 mL/kg) if injection volume is not a major concern 2.
- For susceptible contacts who are pregnant or immunocompromised, IMIg can be provided at a concentration of 0.5 mL/kg, or intravenous immunoglobulin (IVIg) can be provided at a dose of 400 mg/kg, if injection volume is a major concern or for recipients 30 kg or more 2, 3.
Effectiveness of Post-Exposure Prophylaxis
- The effectiveness of MMR vaccine as post-exposure prophylaxis was found to be 83.4% (95% CI, 34.4%, 95.8%) in one study 4.
- The effectiveness of immune globulin (IG) as post-exposure prophylaxis was found to be 100% (approximated 95% CI, 56.2%, 99.8%) in one study 4.
- A systematic review found that estimates of effectiveness ranged from 76% (95% CI 0-94) to 100% (95% CI 56.2-99.8%) for IG PEP, and from 83.4% (95% CI 34.4-95.8) to 100% (95% CI not estimable) for MCV PEP 5.
Special Populations
- For immunocompromised or pregnant individuals, the data on post-exposure prophylaxis is limited, and future research should seek to estimate effectiveness in these populations 5.
- One study found that IVIG PEP was effective in preventing measles in infants, with an effectiveness of 99.3% (CI 95%: 88.7-100%) 6.