Table 2. Primary Outcomes of Confirmed Infection and Severe Illness.^*.

Outcome	Nonbooster Group	Booster Group	Adjusted Rate Ratio (95% CI)†
Confirmed infection			11.3 (10.4–12.3)
No. of cases	4439	934
No. of person-days at risk	5,193,825	10,603,410
Severe illness			19.5 (12.9–29.5)
No. of cases	294	29
No. of person-days at risk	4,574,439	6,265,361

^*Listed are the results of the Poisson regression analysis in participants who received a booster vaccine and in those who did not receive a booster. The booster group includes data that were obtained at least 12 days after receipt of the booster dose.

^†The rate ratio is the estimated factor reduction in the rate in the booster group as compared with the rate in the nonbooster group.