Accurate SARS-CoV-2 seroprevalence surveys require robust multi-antigen assays
Christos Fotis, Nikolaos Meimetis, Nikos Tsolakos, Marianna Politou, Karolina Akinosoglou, Vaia Pliaka, Angeliki Minia, Evangelos Terpos, Ioannis P. Trougakos, Αndreas Mentis, Markos Marangos, George Panayiotakopoulos, Meletios Α. Dimopoulos, Charalampos Gogos, Alexandros Spyridonidis, Leonidas G. Alexopoulos
Abstract
There is a plethora of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) serological tests based either on nucleocapsid phosphoprotein (N), S1-subunit of spike glycoprotein (S1) or receptor binding domain (RBD). Although these single-antigen based tests demonstrate high clinical performance, there is growing evidence regarding their limitations in epidemiological serosurveys. To address this, we developed a Luminex-based multiplex immunoassay that detects total antibodies (IgG/IgM/IgA) against the N, S1 and RBD antigens and used it to compare antibody responses in 1225 blood donors across Greece. Seroprevalence based on single-antigen readouts was strongly influenced by both the antigen type and cut-off value and ranged widely [0.8% (95% CI 0.4-1.5%)-7.5% (95% CI 6.0-8.9%)]. A multi-antigen approach requiring partial agreement between RBD and N or S1 readouts (RBD&N|S1 rule) was less affected by cut-off selection, resulting in robust seroprevalence estimation [0.6% (95% CI 0.3-1.1%)-1.2% (95% CI 0.7-2.0%)] and accurate identification of seroconverted individuals.