What determines immunity to measles (rubeola)?

From the Guidelines

Immunity to measles is primarily determined by documentation of two doses of the MMR vaccine, birth before 1957, laboratory evidence of immunity, or documentation of physician-diagnosed measles. The most common method to determine immunity is through a measles IgG antibody test, which detects antibodies developed after exposure to the virus through natural infection or vaccination 1. A positive result indicates immunity, while a negative result suggests susceptibility to measles. Healthcare providers consider individuals immune if they meet the above criteria. For those with uncertain immunity status, getting the MMR vaccine is generally recommended, as receiving additional doses is safe for most people 1. The MMR vaccine is administered as two doses, typically given at 12-15 months and 4-6 years of age, but can be given to adults who need protection. Some key points to consider include:

• Adults born before 1957 are generally considered immune to measles 1
• Adults born during or after 1957 should receive 1 or more doses of MMR unless they have a medical contraindication, documentation of 1 or more doses, history of measles based on health care provider diagnosis, or laboratory evidence of immunity 1
• A second dose of MMR is recommended for adults who have been recently exposed to measles or are in an outbreak setting, have been vaccinated previously with killed measles vaccine, have been vaccinated with an unknown type of measles vaccine during 1963–1967, are students in postsecondary educational institutions, work in a health care facility, or plan to travel internationally 1. Immunity develops because the vaccine contains weakened live viruses that stimulate the immune system to produce protective antibodies without causing the disease itself. It's worth noting that while other studies provide similar information, the most recent and highest quality study is from 2009, which provides the most up-to-date recommendations for measles immunity 1.

From the Research

Determinants of Immunity to Measles

The immunity to measles (rubeola) is determined by several factors, including:

• The presence of specific antibodies, which can be induced by measles vaccination or natural infection 2, 3
• The level of antibody titers, with higher titers indicating greater immunity 2, 3
• The avidity of antibodies, with higher avidity indices indicating greater immunity 4
• The type of vaccine used, with different vaccines inducing different levels of immunity 4, 3
• The timing of vaccination, with earlier vaccination inducing lower avidity indices 4

Role of Vaccination in Immunity

Vaccination plays a crucial role in inducing immunity to measles, with:

• Measles-specific enzyme-linked immunosorbent assay (ELISA)-IgG avidity test able to discriminate nonresponders, primary responders, and those previously immunized 4
• Measles vaccination inducing a long-lasting immune protection, with specific antibodies associated with this protection 2
• Post-exposure prophylaxis (PEP) with measles-containing vaccine (MCV) or immunoglobulins (Ig) able to prevent measles infection in susceptible individuals 3, 5

Factors Influencing Immunity

Several factors can influence immunity to measles, including:

• Age, with children and teenagers proposing to have cross-protection against COVID-19 due to prior immunization with measles, mumps, and rubella vaccines 6
• Prior immunization with measles, mumps, and rubella vaccines, which may contribute to the antibody response to COVID-19 antigens 6
• Intensity of exposure, time from exposure to treatment, and dose of Ig, which are poorly reported in studies and may affect the effectiveness of PEP 5