From the Guidelines
Immunity to measles is primarily determined through documentation of two doses of the MMR vaccine, laboratory evidence of immunity, or birth before 1957. The most common method to check for measles immunity is through a measles IgG antibody test, which detects antibodies produced by the immune system in response to either vaccination or previous infection 1. A positive result indicates immunity, while a negative result suggests a lack of immunity.
Determining Immunity
To determine immunity, healthcare providers consider several factors, including:
- Documentation of two doses of the MMR vaccine
- Laboratory evidence of immunity to measles
- Birth before 1957, as most people were exposed naturally
- History of measles based on healthcare provider diagnosis
Vaccination Recommendations
For those found to be non-immune, vaccination with the MMR vaccine is advised, typically given as two doses separated by at least 28 days 1. A second dose of MMR is recommended for adults who have been recently exposed to measles, are in an outbreak setting, or have other specific risk factors.
Importance of Measles Immunity
Measles immunity is crucial because the disease is highly contagious and can cause serious complications, particularly in young children and individuals with weakened immune systems. Having a high percentage of immune individuals in the population helps prevent outbreaks through herd immunity 2.
Clinical Considerations
In clinical practice, it is essential to assess immunity status, especially in individuals at high risk for exposure or complications, and to recommend vaccination accordingly 1. This approach helps prevent measles outbreaks and protects vulnerable populations.
From the Research
Determinants of Immunity to Measles
- Immunity to measles is determined by the presence of specific antibodies, which can be induced through vaccination or natural infection 3, 4
- The measles vaccine is highly effective in inducing immunity, with high levels of population immunity needed to prevent outbreaks 5, 4
- The second dose of the measles-containing vaccine (MCV2) and doses given during supplementary immunization activities (SIAs) play a crucial role in achieving high levels of population immunity 5
Role of Antibody Avidity in Measles Immunity
- Antibody avidity, measured by enzyme-linked immunosorbent assay (ELISA)-IgG avidity test, can distinguish between primary responders and those previously immunized 6
- Low avidity indices (LAI) are observed in primary vaccinees, while high avidity indices are seen in those previously immunized 6
Methods for Evaluating Measles Immunity
- The neutralization test (NT) is considered the gold standard for measuring measles immunity, while ELISA is a useful tool for identifying seronegative individuals and evaluating vaccine efficacy 3
- ELISA has high sensitivity and specificity compared to NT, although false negative results can occur in individuals with low levels of neutralizing antibody 3