Objectives: To investigate the relationship between the dynamic changes of serum 2019-nCoV IgM/IgG and immunity alteration for patients after 6-month hospital discharge.
Methods: One IgM(+) and IgG(-), 32 IgM(+) and IgG(+), 38 IgM(-) and IgG(+), and 40 IgM(-) and IgG(-) patients were included. Demographic data were collected. IgM and IgG antibodies, hypersensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6) and lymphocyte subsets in serum were determined at weeks 0, 2 and 4.
Results: The hs-CRP and IL-6 levels of all patients were within the normal ranges. The number of patients with all lymphocyte subset testing items within normal ranges was 12/110 (10.9%) at week 0, 15/110 (13.6%) at week 2 and 18/110 (16.4%) at week 4. The percentages of CD8 + cells, NK cells and B lymphocytes in the IgM(+) and IgG(+) group were quite different from those in the IgM(-) and IgG(+) group and the IgM(-) and IgG(-) group, with much higher percentages of CD8 + cells and much lower percentages of NK cells and B lymphocytes at weeks 0, 2 and 4. Twelve IgM(+) patients in the IgM(+) and IgG(+) group converted to IgM(-), and the percentages of NK cells and B lymphocytes in these patients were significantly increased at week 4.
Conclusions: The changes of serum IgM and IgG are closely related to immunity in patients in the recovery stage. However, immunity does not recover when the patients test negative for these antibodies.
Keywords: Antibodies; COVID-19; Immunity; Recovery stage.