Analysis of measles-mumps-rubella (MMR) titers of recovered COVID-19 patients

The measles-mumps-rubella (MMR) vaccine has been theorized to provide
protection against COVID-19. Our aim was to determine whether any MMR IgG
titers are inversely correlated with severity in recovered COVID-19
patients previously vaccinated with MMR II. We divided 80 subjects into
two groups, comparing MMR titers to recent COVID-19 severity. The MMR II
group consisted of 50 subjects who would primarily have MMR antibodies
from the MMR II vaccine, and a comparison group of 30 subjects who would
primarily have MMR antibodies from sources other than MMR II, including
prior measles, mumps, and/or rubella illnesses. There was a significant
inverse correlation (rs = -0.71, P < .001) between mumps titers and
COVID-19 severity within the MMR II group. There were no correlations
between mumps titers and severity in the comparison group, between mumps
titers and age in the MMRII group, or between severity and measles or
rubella titers in either group. Within the MMR II group: mumps titers of
134 to 300 AU/ml (n=8) were only found in those who were functionally
immune or asymptomatic; all with mild symptoms had mumps titers below 134
AU/ml (n=17); all with moderate symptoms had mumps titers below 75 AU/ml
(n=11); all who had been hospitalized and required oxygen had mumps titers
below 32 AU/ml (n=5). Our results demonstrate that there is a significant
inverse correlation between mumps titers from MMR II and COVID-19
severity.