Table 1. Plant attributes and results of company-initiated testing.

Plant	Workforce size	Number shifts	Plant age	Day*	No. tested	IgM	IgG
A	1128	1	<5 years	9	298	9.4% (6.1–12.7%)	6.4% (3.6–9.2%)
B	2400	2	>50 years	46	472	19.0% (15.4–22.5%)	35.8% (31.5–40.1%)
C	750	1	<5 years	25	392		16.6% (12.9–20.3%)
				81	218		29.8% (23.7–35.9%)

Results of company-initiated testing include timing, sample size, and the percent positive to PCR and antibody testing at each plant. 95% confidence intervals are shown in parenthesis.

* Day testing concluded (counted from earliest date with 5 cumulative cases).