From the Guidelines
IgM antibodies typically appear within 7-14 days after receiving the MMR vaccine, with approximately 90%--95% of recipients developing protective antibody within 2 weeks of the dose 1. This timeframe is based on the body's normal immunological process, where IgM is produced first during a primary immune response. The MMR vaccine stimulates the immune system by introducing weakened forms of the measles, mumps, and rubella viruses, prompting B cells to differentiate into plasma cells that secrete these protective antibodies. Some key points to consider include:
- The IgM response is relatively short-lived, usually peaking around 2-3 weeks post-vaccination and then declining over the following weeks as IgG antibodies become the predominant antibody class.
- Individual immune responses may vary based on age, health status, and previous exposure to these viruses or vaccines.
- While IgM indicates a recent vaccination or infection, the development of IgG antibodies (which typically appear slightly later) is more important for long-term immunity against these diseases.
- A second dose of the MMR vaccine is recommended to provide another opportunity to develop immunity in the limited proportion of recipients who fail to respond to the first dose 1.
From the Research
IgM Antibody Response After MMR Vaccine
- The provided studies do not directly address the speed at which IgM antibodies appear after the MMR vaccine.
- However, studies on other vaccines and infections provide some insight into IgM antibody responses.
- For example, a study on SARS-CoV-2 vaccine found that IgM antibody responses were detectable after the second dose of vaccination, but the seropositive rate was relatively low (3.1%) 2.
- Another study on COVID-19 patients found that IgM antibodies started appearing from day five post-infection and peaked around day 35 post-onset of disease (POD) 3.
Comparison with IgG Antibody Response
- In general, IgG antibody responses tend to be more pronounced and longer-lasting than IgM responses.
- A study on the SARS-CoV-2 vaccine found that IgG antibody levels were significantly higher than IgM levels after the second dose of vaccination 2.
- The same study found that IgG antibody responses could be induced by the inactivated SARS-CoV-2 vaccine in healthy individuals, and the response was influenced by age and detection time after the second dose of vaccination 2.
MMR Vaccine-Specific Studies
- While there are no direct studies on IgM antibody responses after the MMR vaccine, studies on the durability of humoral immune responses to rubella following MMR vaccination provide some insight into the immune response.
- A study found that rubella-specific IgG antibody titers, neutralizing antibody titers, and memory B cell responses declined with increasing time since vaccination, but the decreases were relatively moderate 4.
- Another study found that a third dose of MMR vaccine resulted in a significant boost of antibody titers in some individuals, with one-third of subjects experiencing a ≥4-fold increase in neutralizing antibody titers one month following vaccination 5.