Methods: Retrospective chart review was performed on three Kings County Hospital Center employees identified as having negative measles titers, despite repeated vaccination with MMR.
Results: Three healthcare workers were identified with negative titers to measles during pre-employment laboratory analysis. All three cases had normal WBC counts/differential (mean WBC counts 6.1 K/uL), negative hepatitis panel and positive HepBs Ab titers. Two cases were female employees who each received a total of 4 MMR doses, with the last doses given on 12/2012 and 2/2014, respectively. Their MMR titers were respectively measured on 4/2015 and 8/2014, showing positive mumps and rubella IgG titers yet negative measles IgG. The third case involved a male employee who received a total of 6 doses of MMR, with the last dose given on 12/2013. His MMR titers were measured on 5/2014, similarly showing positive mumps and rubella IgG titers; however, measles IgG titer was equivocal—with negative repeat measles IgG on 6/2014. His serum CD3/CD4/CD8/B & T cell counts were normal. There was no history of immunodeficiency or recurrent infections in all three cases.
Conclusions: We identified three cases of negative measles titers in otherwise healthy healthcare workers after repeated vaccination. Consensus to further evaluation of otherwise healthy individuals with negative laboratory vaccine response has not been established.