Table 2. Risk of SARS-CoV-2 Omicron (BA.1 lineage) variant infection among people who received booster vaccination relative to booster-eligible people, according to history of a documented prior SARS-CoV-2 infection.
| Adjustedb | Unadjusted | |||||
|---|---|---|---|---|---|---|
| Prior SARS-CoV-2 infection history and vaccination statusa | Cases | Controls | Odds ratioc | P value | Odds ratioc | P value |
| With a documented prior infection d | ||||||
| Booster-eligible, ≥150 days after second dose (pre-booster dose)e | 204 | 3,342 | - | - | - | - |
| Boosted, ≥14 days after booster (third) dosef | 37 | 643 | 0.79 (0.54, 1.16) | 0.222 | 0.94 (0.66, 1.35) | 0.748 |
| Without a documented prior infection d | ||||||
| Booster-eligible, ≥150 days after second dose (pre-booster dose)e | 3,421 | 38,446 | - | - | - | - |
| Boosted, ≥14 days after booster (third) dosef | 549 | 9,920 | 0.54 (0.49, 0.59) | <0.001 | 0.62 (0.57, 0.68) | <0.001 |
aDue to booster eligibility at the time of the analysis, this analysis was limited to persons 12 years or greater, resulting in the exclusion of 6 booster-eligible controls.
bAdjusted for date of test, age, sex, race/ethnicity, insurance, Charlson Comorbidity Score, SVI (Social Vulnerability Index) of zip code, municipality, and number of nonemergent visits during the year prior to vaccine rollout in Connecticut (December 2, 2019 and December 1, 2020) in all analyses and time between testing and last a documented prior infection in analyses of people with a documented prior infection.
cPoint estimate (95% confidence interval).
dDocumented prior infection defined as a positive RT-PCR or rapid antigen test at least 90 days prior to included test.
eLimited to booster-eligible people, booster-eligible defined as primary series recipients aged 12 years or more who completed their primary series (2 doses) 150+ days prior to the test and were yet to receive a booster (third) dose; 150 days was selected as it reflects the CDC booster recommendations at the time of manuscript submission.
fTen tests (all controls) were collected among people with a documented prior infection that occurred following their booster dose and were removed from this analysis.