1.SARS-CoV-2 seroprevalence and antibody trends in vaccinated, multi-ethnic healthcare employees
Beh, C.C. ; Zulkufli, N.S. ; Loh, L.M. ; Cheng, K.W. ; Choo, L.M. ; Cheah, M.W. ; Siow, L.K. ; Yon, R.
Tropical Biomedicine 2021;38(No.4):552-560
Understanding of antibody kinetics against SARS-CoV-2 and its vaccines is rapidly evolving.
This study aims to (1) determine post-vaccination seroprevalence; (2) compare antibody
levels between vaccine types and various clinical/demographic determinants; and (3)
determine post-vaccination antibody concentrations against time. This is a retrospective
cross-sectional study involving 148 healthcare employees all over Malaysia. IgG Spike (RBD),
IgM Spike and IgG Nucleocapsid concentration medians were compared using Mann-Whitney
U or Kruskal-Wallis tests. Chi Square and Spearman correlation coefficient tests were
performed to identify variables associated with antibody titers. A scatter plot of IgG Spike
(RBD) against time from last vaccine dose was also plotted. At 1-month post-vaccination, all
employees successfully seroconverted regardless of vaccine type, health status and COVID19 history. Comirnaty, convalescent, female or Malay vaccinees had significantly higher IgG
Spike (RBD) titers compared to their respective counterparts. No correlation was found
between age and IgG Spike (RBD) levels. Concentration of all three antibodies waned with
time post-vaccination, with IgM Spike and IgG Nucleocapsid waning faster than IgG Spike
(RBD).