Table 2. Protein specificity of anti-SARS-CoV-2 antibodies detected in healthy individuals non-vaccinated and never diagnosed positively for SARS-CoV-2 infection.

Number of individuals demonstrating indicated specificity was presented.

	anti-NCP	anti-RBD	anti-S2	anti-E	anti-ACE2	anti-PLPro
IgG	136	128	135	1	1	3
IgA	182	136	121	14	20	14

NCP- nucleocapsid protein, RBD-receptor binding domain within Spike protein, S2- domain S2 within Spike protein, E- envelope protein, ACE2- angiotensin-converting enzyme 2, PLPro- papain-like protease.