Table 5.

Estimation of VE_a Over Successive Time Periods Under Different Reverse-Transcription Polymerase Chain Reaction Testing Schedules When Vaccine Efficacy Wanes Over Time

Outside Vaccines	Frequency of Tests	Weeks	True VEa (%)	Proposed Method				Naive Method
				Mean (%)	SE (%)	SEE (%)	CP (%)	Mean (%)	SE (%)	SEE (%)	CP (%)
No	Daily	0–6	50.3	49.3	4.60	4.61	95	49.3	4.60	4.56	95
		6–12	77.7	77.0	3.81	3.84	95	77.0	3.81	3.81	95
		12–18	72.4	72.1	7.69	7.57	95	72.1	7.69	7.57	95
	Every 4 days	0–6	50.3	49.4	4.61	4.66	95	48.0	4.68	4.68	92
		6–12	77.7	77.2	3.82	3.84	94	76.2	3.89	3.88	93
		12–18	72.4	72.3	8.21	7.99	95	72.9	7.86	7.65	95
	Weekly	0–6	50.3	49.4	4.44	4.61	96	46.5	4.61	4.73	88
		6–12	77.7	77.1	3.70	3.83	95	75.1	3.85	3.95	90
		12–18	72.4	72.2	7.61	7.50	96	73.3	7.05	6.99	96
Yes	Daily	0–6	50.3	49.3	4.52	4.62	95	49.3	4.52	4.56	95
		6–12	77.7	77.0	3.85	3.86	95	77.0	3.85	3.83	95
		12–18	72.4	72.0	7.90	7.81	95	72.0	7.90	7.80	95
	Every 4 days	0–6	50.3	49.4	4.67	4.65	94	47.9	4.73	4.67	92
		6–12	77.7	77.0	3.84	3.87	96	76.2	3.89	3.89	94
		12–18	72.4	71.8	8.41	8.34	95	72.8	7.94	7.89	95
	Weekly	0–6	50.3	49.4	4.56	4.61	96	46.5	4.70	4.73	88
		6–12	77.7	77.1	3.93	3.86	95	75.2	4.05	3.95	89
		12–18	72.4	72.0	7.82	7.84	96	73.6	7.10	7.11	96

Mean and SE denote the mean and standard error of the vaccine efficacy (VE) estimator, SEE denotes the mean of the standard error estimator, and CP denotes the coverage probability of the 95% confidence interval.

Abbreviation: VE_a, vaccine efficacy on attack rate.