Mumps outbreak and MMR IgG surveillance as a predictor for immunity in military trainees

Abstract

In 2017, a mumps outbreak occurred in a barrack holding 249 service members. Suspected cases were evaluated with a combination of mumps IgG, IgM, viral culture, PCR and sequencing. Seven cases were diagnosed in febrile patients presenting with parotitis or orchitis. Mumps infection was confirmed by IgM or positive PCR with 5/7 cases having notable IgG levels before infection. Sequencing confirmed mumps genotype G strain. Serum from all 249 service members collected prior to the outbreak was withdrawn from the Department of Defense (DoD) Serum Repository and the IgG values of measles, mumps and rubella determined with 20.2%, 12.3% and 9.7% service members being seronegative, respectively. No specific IgG seronegativity combination predicted IgG marker levels to another virus within the same vaccine. This paper provides additional evidence that mumps serology is not a reliable surrogate for mumps immunity and that we need better laboratory correlates to confirm immunity.

Keywords: IgG Titer; MMR vaccine; Measles; Mumps; Rubella.