TABLE 2.

Simulated performance of surveillance anchored sieve analysis for an idealized two period deferred vaccination design

	Ancestral strain		Variant strain		Test $H_0^{(W)}$		Test $H_0^{(S)}$
Scenario	VE${}_{10}$	VE${}_{20}$	VE${}_{11}$	VE${}_{21}$	$S=0$	$S=1$	Period 1	Period 2
1. Reference	0.8998	0.8955	0.8955	0.8958	0.0499	0.0451	0.0475	0.0460
	(0.0105)	(0.0336)	(0.0337)	(0.0337)
2. Waning VE	0.9000	0.7909	0.7902	0.5814	0.8235	0.9856	0.8055	0.9709
	(0.0105)	(0.0598)	(0.0609)	(0.1143)
3. $p_{20}=0.80$	0.8999	0.8868	0.8868	0.8870	0.0415	0.0496	0.0373	0.0438
	(0.0105)	(0.0626)	(0.0540)	(0.0546)
4. $p_{20}/p_{21}=1.50$ a	0.8998	0.8954	0.8429	0.8425	0.0469	0.0477	0.2856	0.2840
	(0.0104)	(0.0332)	(0.0519)	(0.0513)
5. $p_{20}/p_{21}=0.67$ a	0.9000	0.8952	0.9298	0.9298	0.0454	0.0470	0.2793	0.2804
	(0.0105)	(0.0336)	(0.0230)	(0.0228)

Note: During period 1 (period 2) the expected actual (counterfactual) placebo case count is 1000 (500). The true VE${}_{KS}=0.90$ except for scenario 2 with VE${}_{11}$, VE${}_{20}$, VE${}_{21}$ = 0.80, 0.80,0.60. The VE columns report the Monte Carlo means and (standard deviations). The right columns report the rejection rates for $H_0^{(W)}:{\text{VE}}_{1S}={\text{VE}}_{2S}$ and $H_0^{(S)}:{\text{VE}}_{K0}={\text{VE}}_{K1}$, respectively, based on a Wald test. 10 000 trials are simulated per row.

^a True ratio is as given but offsets incorrectly use ratio of 1.00.