From the Guidelines
Measles Antibody Titers in Adults
Measles titers are typically considered protective if they are greater than or equal to 1:10. Adults born before 1957 are generally considered immune to measles, while those born in 1957 or later should have documentation of 1 or more doses of MMR vaccine, unless they have a medical contraindication or laboratory evidence of immunity 1.
- Key factors influencing measles immunity include:
- Birth year: Adults born before 1957 are generally considered immune 1.
- Vaccination history: Documentation of 1 or more doses of MMR vaccine is recommended for adults born in 1957 or later, unless they have a medical contraindication or laboratory evidence of immunity 1.
- Occupational or educational exposure: Adults who work in healthcare facilities, are students in postsecondary educational institutions, or plan to travel internationally may require a second dose of MMR vaccine, administered a minimum of 28 days after the first dose 1. If an adult's measles titer is less than 1:10, or if the titer is unknown, the Centers for Disease Control and Prevention (CDC) recommends administering 2 doses of the measles, mumps, and rubella (MMR) vaccine, separated by at least 28 days, to ensure adequate immunity. Alternatively, if the adult has a medical contraindication to the MMR vaccine, they may be considered immune if they have a documented history of measles infection or have received 2 doses of the measles vaccine in the past. In cases where vaccination is not possible, immune globulin may be administered as post-exposure prophylaxis, with a dose of 0.25 mL/kg of body weight, up to a maximum of 15 mL, administered within 6 days of exposure.
From the Research
Measles Antibody Titers in Adults
- The measles-neutralizing antibody titers in adults can vary depending on the individual's vaccination history and the presence of natural infection 2, 3, 4, 5, 6.
- Studies have shown that adults who received one or two doses of the measles-mumps-rubella (MMR) vaccine can have a range of antibody titers, with some individuals having low or undetectable levels of neutralizing antibodies 2, 3, 5.
- A study found that 2 years after vaccination, 45.8% of participants had a medium (121-900) or high (>900) plaque reduction neutralization (PRN) titer, while 82.2% had a seroconversion rate of measles IgGs 2.
- Another study found that 1 year after receiving a third MMR dose, no subject was seronegative, and 10 of 617 (1.6%) had low neutralizing antibody levels 3.
- Long-term studies have shown that vaccine-induced antibody to measles can persist for 26-33 years after vaccination, with 92% of participants having a PRN titer considered protective (>1:120) 4.
- A study found that 11 years after receiving a third MMR dose, measles and rubella neutralizing antibody levels remained high in adults, but some individuals may become susceptible to measles infection over time despite receipt of 3 vaccine doses 5.
- The protective titers of measles neutralizing antibody have been defined as >1,000 mIU/ml to prevent measles infection and >500 mIU/ml to prevent symptomatic infection 6.
Factors Influencing Antibody Titers
- Vaccination history: The number of doses and timing of MMR vaccination can influence antibody titers 2, 3, 4, 5.
- Natural infection: Individuals with a history of natural infection tend to have higher antibody titers than those who have only been vaccinated 2.
- Time since vaccination: Antibody titers can wane over time, with some individuals becoming susceptible to measles infection despite previous vaccination 3, 5.