Is it possible to accelerate Measles, Mumps, and Rubella (MMR) vaccine dosing in response to a measles outbreak?

From the Guidelines

Accelerated MMR vaccination is possible and recommended during measles outbreaks, with infants as young as 6 months receiving a single dose and unvaccinated individuals over 12 months receiving two doses separated by at least 28 days. The standard schedule can be modified to provide faster protection to vulnerable populations when measles is actively circulating 1. According to the Advisory Committee on Immunization Practices, during a measles outbreak, infants aged 6–11 months should receive a single dose of MMR, and for measles postexposure prophylaxis in unvaccinated persons, 1 dose of MMR should be administered within 72 hours of exposure to a person with infectious measles, and the 2-dose series should be completed ≥28 days later 1.

Key points to consider:

• Infants vaccinated before 12 months will still need two additional doses at the regularly scheduled times, as early vaccination may not produce optimal immunity due to interference from maternal antibodies.
• The MMR vaccine is highly effective, with about 93% protection after one dose and 97% after two doses, making it crucial for outbreak control.
• Side effects are generally mild and include fever, rash, or temporary joint pain.
• The accelerated schedule is supported by the Infectious Diseases Society of America, which recommends that vaccine doses administered 4 days before the minimum interval or age be counted as valid 1.
• Simultaneous administration of all indicated vaccines is important to increase the probability that a child or adult will be appropriately immunized, especially during outbreaks or when preparing for foreign travel 1.

From the Research

Accelerating MMR Vaccine Dosing in Response to a Measles Outbreak

• The World Health Organization recommends a two-dose strategy for the Measles, Mumps, and Rubella (MMR) vaccine, which is widely adopted in many countries 2.
• A study found that administering the first dose of MMR vaccine at 8 months versus 12 months age in children resulted in similar immunogenicity, suggesting that accelerating the dosing schedule may be effective in response to a measles outbreak 2.
• Another study found that children who received an early dose of MMR vaccine during a measles outbreak were more likely to return for their regularly scheduled dose, with 96.5% coverage for the routine dose at age 24 months 3.
• The effectiveness of the MMR vaccine in preventing clinical measles is estimated to be at least 95% after one dose, and 92% effective in preventing secondary cases among household contacts 4.
• The safety of the MMR vaccine has been evaluated in several studies, with mild and transient adverse events reported, including headache, joint problems, diarrhea, and lymphadenopathy 5, 6.

Key Findings

• Accelerating the MMR vaccine dosing schedule may be effective in response to a measles outbreak, with similar immunogenicity observed when administering the first dose at 8 months versus 12 months age 2.
• Children who receive an early dose of MMR vaccine during a measles outbreak are likely to return for their regularly scheduled dose 3.
• The MMR vaccine is highly effective in preventing clinical measles and secondary cases among household contacts 4.
• The safety profile of the MMR vaccine is well-established, with mild and transient adverse events reported 5, 6.

Implications for Vaccine Administration

• Accelerating the MMR vaccine dosing schedule may be considered in response to a measles outbreak, particularly in areas with high transmission rates 2, 3.
• Healthcare providers should ensure that children who receive an early dose of MMR vaccine return for their regularly scheduled dose to maintain optimal protection against measles, mumps, and rubella 3.
• The MMR vaccine should be administered according to the recommended schedule, with two doses given at least 28 days apart, to provide optimal protection against the target diseases 4, 6.