Overview of Laboratory Confirmation by IgM Serology

Laboratory confirmation of mumps in previously vaccinated or previously infected individuals is challenging, and failure to detect mumps IgM in previously vaccinated persons has been well documented.

Persons with a history of mumps vaccination may not have detectable mumps IgM antibody regardless of timing of specimen collection.

The ability to detect IgM varies by vaccination status and is highest in unvaccinated persons (80%–100%) (Sakata et al. 1985), intermediate in one-dose vaccine recipients (60%–80%) (Briss et al. 1994; Narita et al. 1998), and lowest in two-dose vaccine recipients (13%–14%) (Bitsko et al. 2008; Rota et al. 2009).

Mumps exposure history	IgM	IgG	Comments	References
Unvaccinated; no history of mumps	+	+ or −	IgM may be detected for weeks to months; low levels of IgG may be present at symptom onset	Meurman et al. 1982; Sakata et al. 1985
1–dose vaccine history	+ or −	Likely +	50% of serum samples collected 1–10 days after symptom onset were IgM-positive; 50%–80% of serum samples collected >10 days after symptom onset were IgM-positive	Narita et al. 1998; Jin et al. 2004; Krause et al. 2007
2–dose vaccine history	+ or −	Likely +	13%–15% of serum samples collected 1–3 days after symptom onset were IgM-positive*	Bitsko et al. 2008; Rota et al. 2009

*30%–35% of buccal samples collected 1–3 days after symptom onset were positive by real-time RT-PCR among persons with 2 doses of MMR (Bitsko et al. 2008; Rota et al. 2009)