Table 2. Positivity rate (%) by screening strategy and difference with the reference strategya.

	Positivity rate × 100 screened subjects
		2–day strategy
Cutoff	1-day strategy	(at least one sample with positive result)	(both samples with positive results)
⩾80 ng ml−1	5.5	8.0	2.8
	+0.9 (0.5–1.4)	+3.5 (3.0–3.9)	−1.7 (−2.1 to −1.4)
⩾100 ng ml−1	4.5a	6.7	2.3
	(reference)	+2.2 (1.7–2.6)	−2.2 (−2.6 to −1.9)
⩾120 ng ml−1	4.0b	5.9	2.0
	−0.5 (−0.9 to −0.1)	+1.4 (1.0–1.8)	−2.5 (−2.8 to −2.2)

Statistical comparison of strategies (with Bonferroni correction for multitesting).

95% CI (confidence interval) of difference is given in brackets.

All differences among each strategy and the reference strategy were statistically significant at P<0.00625 (threshold for significance after Bonferroni correction), except strategy of 1-day and cutoff ⩾120 ng ml⁻¹.

^aReference strategy: 1-day and cutoff ⩾100 ng ml⁻¹.

^bP=0.0113.