Abstract
Molecular assays on nasopharyngeal swabs act as the confirmatory test in
CoronaVIrus Disease (COVID-19) diagnosis. Despite massive efforts had
been made, the high technicalities of nasopharyngeal sampling and
molecular assays limit the testing capabilities. Currently, the use of
saliva for diagnosis has been recently suggested for COVID-19 diagnostic
testing. In a recent research, salivary IgA was associated with the
presence of pneumonia, which might illuminate that salivary IgA was
independent from serum immunoglobulins. In this study, a total of 44
patients diagnosed with COVID-19 in the Third People’s Hospital of
Shenzhen were enrolled. Saliva specimens and serum specimens were
obtained at different time points and the immunoglobulins against the
SARS-CoV-2 was measured. The results showed that saliva IgA presented
higher COI value than IgG and IgM. In matched saliva and serum samples,
all saliva presented lower IgG level than serum, and only one saliva
sample presented higher IgM level. The conversion rates of saliva IgA
and the detection of viral nucleic acid were analyzed in the first and
second week after hospitalization. The positive rates were obviously
increased when combining the saliva IgA and viral nucleic acid
detection. Saliva IgA could serve as useful index for early diagnosis of
COVID-19.