From the Research
The measles vaccine given at 6 months of age typically takes about 2-3 weeks to develop protective immunity, though this early vaccination provides only partial protection. When administered at this young age, the vaccine is less effective than when given at the recommended age of 12-15 months because maternal antibodies can interfere with the immune response 1. This early dose is considered an "extra" dose and not part of the standard vaccination schedule except in special circumstances like outbreaks or travel to high-risk areas. Children vaccinated at 6 months will still need the standard two doses at 12-15 months and 4-6 years of age to ensure full protection. The immune system of a 6-month-old is still developing, which also contributes to the reduced effectiveness of the vaccine at this age. Some key points to consider:
- The effectiveness of the measles vaccine in preventing measles was 95% after one dose and 96% after two doses 2.
- The vaccine effectiveness in preventing cases among household contacts or preventing transmission to others the children were in contact with after one dose was 81% and after two doses 85% 2.
- Infants vaccinated with MCV1 < 12 months of age showed an overall higher risk of measles compared to ≥12 months of age 1. Despite providing only partial protection, this early vaccination can be valuable in high-risk situations to provide some immunity until the child can receive the standard doses. It is essential to follow the recommended vaccination schedule to ensure full protection against measles and other vaccine-preventable diseases.