Table 2.

Effectiveness^a of Third Doses of BNT162b2 or mRNA-1273^b Against Symptomatic SARS-CoV-2 Infection in California, February to November 2021

	Cases		Controls
Exposure	No.	%	No.	%	Absolute VE vs. 0 Doses	95% CI	Relative VE of 3 Doses vs. Indicated Exposure	95% CI
0 doses	942	83.6	842	64.9	1.0	Referent	95.0	82.8, 98.6
2 doses (fully vaccinated)
Fully vaccinated 1 month prior	12	6.5	88	19.3	89.2	80.7, 94.4	71.6	−45.4, 94.3
Fully vaccinated 2 months prior	19	10.3	82	18.0	82.4	71.2, 89.8	81.1	11.7, 96.0
Fully vaccinated 3 months prior	27	14.6	74	16.2	75.4	61.2, 84.8	84.1	33.6, 96.4
Fully vaccinated 4 months prior	28	15.1	56	12.3	72.3	55.5, 83.2	85.9	42.8, 96.6
Fully vaccinated 5 months prior	22	11.9	39	8.6	71.3	50.0, 83.9	84.4	37.1, 96.3
Fully vaccinated 6 months prior	27	14.6	45	9.9	70.1	49.7, 82.5	85.0	40.5, 96.4
Fully vaccinated 7 months prior	24	13.0	28	6.1	65.0	36.0, 81.0	85.3	41.1, 96.4
Fully vaccinated 8 months prior	23	12.4	22	4.8	58.4	19.9, 78.3	87.9	51.9, 97.0
3 doses
3 doses ≥7 days before testing	3	0.3	22	1.7	95.0	82.8, 98.6

Abbreviations: CI, confidence interval; VE, vaccine effectiveness.

^a Logistic regression model adjusting for age, sex, region, week of testing, and presence of immunocompromising or comorbid conditions used to assess the adjusted odds ratio of each vaccine exposure category (defined categorically by months since individuals were considered fully vaccinated), defining the reference exposure as receipt of 0 doses (for absolute VE) or as receipt of 2 doses at each indicated time interval (for recipients of 3 doses). Descriptive characteristics of 3 dose recipients are listed in Web Table 6.

^b BNT162b2 (Pfizer/BioNTech, New York, New York) or mRNA-1273 (Moderna, Cambridge, Massachusetts).