. 2021 May 6;325(24):1–9. doi: 10.1001/jama.2021.7152

Table 2. Observed Incidence Rate Ratios of Symptomatic and Asymptomatic SARS-CoV-2 Infection^a.

Vaccination status	Subgroup	Vaccinated				Unvaccinated^b				Incidence rate ratio (95% CI)^c		P value
Vaccination status	Subgroup	No. of cases	No.	Surveillance time, person-days	Incidence rate per 100 000 person-days^c	No. of cases	No.	Surveillance time, person-days	Incidence rate per 100 000 person-days^c	Unadjusted^d	Adjusted^e	P value
Original cohort
Fully vaccinated^f	Symptomatic	8	5372	168 571	4.7	38	696	25 359	149.8	0.03 (0.01-0.07)	0.03 (0.01-0.06)	<.001
Fully vaccinated^f	Asymptomatic	19	5372	168 571	11.3	17	696	25 359	67.0	0.17 (0.09-0.32)	0.14 (0.07-0.31)	<.001
Late fully vaccinated^g	Symptomatic	2	5036	95 689	2.1	23	675	15 726	146.3	0.01 (0-0.06)	0.02 (0-0.06)	<.001
Late fully vaccinated^g	Asymptomatic	4	5036	95 689	4.2	11	675	15 726	69.9	0.06 (0.02-0.19)	0.06 (0.02-0.22)	<.001
Partially vaccinated^h	Symptomatic	31	5761	117 389	26.4	37	741	15 091	245.2	0.11 (0.07-0.17)	0.11 (0.06-0.17)	<.001
Partially vaccinated^h	Asymptomatic	37	5761	117 389	31.5	8	741	15 091	53.0	0.59 (0.28-1.28)	0.64 (0.31-1.51)	.27
Propensity score–matched adjusted cohort
Fully vaccinated^f	Symptomatic	2	1916	57 274	3.5	38	696	25 359	149.8	0.02 (0.01-0.10)	0.02 (0-0.07)	<.001
Fully vaccinated^f	Asymptomatic	4	1916	57 274	7.0	17	696	25 359	67.0	0.10 (0.04-0.31)	0.09 (0.03-0.25)	<.001
Late fully vaccinated^g	Symptomatic	1	1748	31 645	3.2	23	675	15 726	146.3	0.02 (0-0.16)	0.02 (0-0.10)	<.001
Late fully vaccinated^g	Asymptomatic	2	1748	31 645	6.3	11	675	15 726	69.6	0.09 (0.02-0.41)	0.09 (0.01-0.35)	.002
Partially vaccinated^h	Symptomatic	4	2085	42 414	9.4	37	741	15 091	245.2	0.04 (0.01-0.11)	0.03 (0.01-0.09)	<.001
Partially vaccinated^h	Asymptomatic	11	2085	42 414	25.9	8	741	15 091	53.0	0.49 (0.20-1.22)	0.48 (0.19-1.26)	.12

^{^a}

Participants with fewer than 7 days of follow-up or who contracted SARS-CoV-2 less than 7 days after the first vaccine dose were not included in this analysis (Figure 2).

^{^b}

The surveillance period used corresponded to the period used for the vaccinated participants (ie, 28, 42, or 7-28 days after the beginning of follow-up, which was set as December 20, 2020).

^{^c}

When estimating incidence rates and incidence rate ratios of symptomatic infection, asymptomatic cases were censored on the day of case confirmation (and vice versa).

^{^d}

Indicates the ratio of incidence rates in each group.

^{^e}

Calculated using Poisson regression as detailed in the Methods section.

^{^f}

Included those with data for longer than 7 days after the second dose to the end of follow-up.

^{^g}

Included those with data for longer than 21 days after the second dose to the end of follow-up.

^{^h}

Included those with data for days 7 to 28 after first dose.

Table 2. Observed Incidence Rate Ratios of Symptomatic and Asymptomatic SARS-CoV-2 Infectiona.

Table 2. Observed Incidence Rate Ratios of Symptomatic and Asymptomatic SARS-CoV-2 Infection^a.