Mumps IgG 10.6: Interpretation of Immunity Status
An IgG mumps result of 10.6 indicates immunity to mumps, as any antibody level above the standard positive cutoff value of the assay is considered acceptable evidence of mumps immunity. 1
Understanding Your Result
Your mumps IgG value of 10.6 represents a positive result that demonstrates protective immunity against mumps virus. 1 The key principle is straightforward: the demonstration of mumps IgG antibody by any commonly used serologic assay is acceptable evidence of mumps immunity, regardless of the specific numeric value, as long as it exceeds the laboratory's positive threshold. 1
What This Result Means Clinically
You are immune to mumps through either previous successful vaccination with mumps-containing vaccine (such as MMR) or past natural mumps infection, both of which provide long-term immunity that is likely to be protective against clinical disease. 1
This is NOT an indication of active or recent mumps infection. 1 IgM antibody testing would be required to diagnose acute mumps infection. 1, 2
No further mumps vaccination is needed based solely on this positive IgG result. 1
This result can be documented as laboratory evidence of mumps immunity for employment requirements, school entry, or healthcare worker credentialing. 1
Important Clinical Context
Antibody Persistence
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 However, research indicates that secondary vaccine failure (waning immunity) can occur, particularly in outbreak settings. 3, 4
Outbreak Considerations
During mumps outbreaks, individuals with positive IgG antibodies like yours are generally considered protected, though breakthrough infections can occasionally occur even in those with documented immunity. 1 Studies show that 12 of 14 patients with mumps vaccine failure had secondary vaccine failure despite prior vaccination. 4
If Symptoms Develop
If you develop symptoms suggestive of active mumps infection (such as parotitis) despite this positive IgG result, IgM antibody testing should be performed immediately. 1 Additionally, viral detection methods including culture or nucleic acid amplification testing (NAAT) from buccal swab may be necessary for diagnosis in previously vaccinated individuals. 1
Common Pitfalls to Avoid
Do not confuse IgG testing (for immunity) with IgM testing (for acute infection). 2 The majority of IgM testing for mumps during 2019-2022 appeared inappropriate, with only 32.8% of mumps IgM tests being appropriately performed in conjunction with diagnostic codes for acute illness. 2
Do not assume that a positive IgG result means you cannot get mumps. 1 Breakthrough infections can occur, particularly during outbreaks, though they remain uncommon.
Do not request repeat IgG testing to "confirm" immunity. 1 Post-vaccination serologic testing to verify immune response is not recommended by CDC guidelines. 5