TABLE 4.

Cross-reactivity of enzyme immunoassays and lateral flow devices with sera from pre-COVID general population and patients diagnosed with unrelated disease

Population	nd	Cross-reactivity for SARS-CoV-2 antigen with the indicated test (no. of positive samples)
		Nucleocapsid			Spike		Spike RBD		Spike S1 and S2 domains, DiaSorin	Spike S1 domain		Not specified
		Abbott	Roche	Bio-Rad	Ortho-Clinical		Beckman	Siemens		Euro-Immun		Biocan	BTNX	NADAL
		IgG	Total Ab	Total Ab	IgG	Total Ab	IgG	Total Ab	IgG	IgA	IgG	IgM/IgG	IgM/IgG	IgM/IgG
General populationa	38	0	0	5	0	0	0	0	0	6	2	0	1	0
SARS-CoV-2 PCR neg	13	0	0	1	0	0	0	0	0	3	1	0	0	0
Coronavirusb	20	0	0	0	0	0	0	0	0	4	2	0	0	1
Rhinovirus	6	0	0	0	0	0	0	0	0	1	0	0	0	0
Enterovirus	2	0	0	0	0	0	0	0	0	0	0	0	0	0
Influenza A virus	3	0	0	0	0	0	0	0	0	2	0	0	0	0
Influenza B virus	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Parainfluenza virus 2/3	2	0	0	0	0	0	0	0	0	0	0	0	1	0
Adenovirus	8	0	0	0	0	0	0	0	0	2	0	0	0	0
RSV	1	0	0	0	0	0	0	0	0	0	0	0	0	0
VZV	1	0	0	0	0	0	0	0	0	0	0	0	0	0
Dengue virus	20	0	0	1	2	1	0	0	0	7	3	0	2	0
Autoimmune disease	39, 51c	0	0	1	1	1	0	1	0	9	1	1	18	3

^aPrior to January 2020.

^bSeasonal coronaviruses include 229E, NL63, OC-43, and HKU-1.

^cEnzyme immunoassays, n = 39; lateral-flow chromatographic assays, n = 51.

^dn, total number of samples.