What does a Mumps Antibody (Mumps Ab), Immunoglobulin G (IgG) level of 52.6 indicate?

Interpretation of Mumps Ab, IgG 52.6

A Mumps Ab, IgG level of 52.6 indicates immunity to mumps virus, either from previous vaccination or natural infection. 1

Understanding Mumps IgG Antibody Results

• The demonstration of mumps IgG antibody by any commonly used serologic assay is acceptable evidence of mumps immunity 1
• Any antibody level above the standard positive cutoff value of the assay with which it is measured can be considered evidence of immunity, if the assay is licensed 1
• Immunity to mumps is suggested by the presence of antimumps IgG-class antibodies 1
• The specific value of 52.6 indicates a positive result that is well above the threshold for immunity in most commercial assays 1

Clinical Significance

• This positive IgG result indicates one of the following:

  • Previous successful vaccination with mumps-containing vaccine (usually MMR) 1
  • Past natural mumps infection 1
  • Long-term immunity that is likely to be protective against clinical disease 1

• This result does NOT indicate:

  • Active or recent mumps infection (IgM testing would be needed for that) 1
  • Need for additional vaccination if the patient has documented receipt of recommended doses 1

Interpretation Considerations

• While mumps antibody levels may wane over time, surveillance data suggest that waning immunity with increased susceptibility to clinical disease does not typically occur 1
• Enzyme immunoassays (EIAs) are the most commonly used commercial assays for mumps IgG detection, having replaced older hemagglutination inhibition (HI) tests 1
• There is sometimes poor correlation between mumps IgG levels measured by ELISA and neutralizing antibody levels, which are considered more directly related to protection 2

Recommendations Based on This Result

• No further testing or vaccination is needed based solely on this positive IgG result 1
• This result can be documented as laboratory evidence of mumps immunity 1
• During mumps outbreaks, individuals with positive IgG antibodies are generally considered protected, though breakthrough infections can occasionally occur 1

Important Considerations

• If the patient has symptoms suggestive of active mumps infection despite this positive IgG result:

  • IgM antibody testing should be performed 1
  • In previously vaccinated patients with suspected mumps, IgM may be negative despite active infection 1
  • Testing for IgA antibodies may increase diagnostic yield in vaccinated individuals with suspected active infection 3
  • Viral detection methods (culture or NAAT) from buccal swab may be necessary for diagnosis in previously vaccinated individuals 1

• For healthcare workers, this positive IgG result meets the criteria for presumptive evidence of immunity to mumps when documented 1