Summarized Characteristics of Included Real-World Studies
| Study (Country) | Study Period | Funding Type (Patient Hospitalization Status) | Total No. of Patients | No. of Patients in Intervention Group (Mean Age), % Male | % of Intervention Group Vaccinated | No. of Patients in Comparator Group (Mean Age), % Male | % of Comparator Group Vaccinated | Outcome (Adjusted Covariates) |
|---|---|---|---|---|---|---|---|---|
| Aggarwal et al,33 2023 (USA) | Mar 26-Aug 25, 2022 | NIH (outpatients) | 21,493 | 9,881 (not reported), 41.4 | 79.6 | 11,612 (not reported), 41.7 | 78.3 | Hospitalization and all-cause mortality at 28 days (age, sex, race, ethnicity, insurance status, obesity status, immunocompromised status, number of additional comorbid conditions, number of vaccinations, Omicron subvariant) |
| Al-Obaidi et al,34 2023 (USA) | Jun 01-Sep 24, 2022 | Not funded (outpatients) | 11,508 | 5,754 (not reported), 39.9 | Not clear | 5,754 (not reported), 41.6 | Not clear | Hospitalization and all-cause mortality at 30 days (vaccination status, body mass index, age, diabetes) |
| Bajema et al,35 2023 (USA) | Jan-Feb 2022 | US Dept of Veterans Affairs Central Office (outpatients) | 104,992 | 1,639 (not reported), 89 | 71 | 103,353 (not reported), 89.3 | 69.8 | Hospitalization or death at 30 days (not clear) |
| Bhatia et al,36a 2023 (USA) | Dec 23, 2021-Dec 31, 2022 | Not clear (outpatients) | 410,642 | 104,510 (not reported), 38.8 | Not reported | 306,132 (not reported), 38.1 | Not reported | Hospitalization at 28 days (sex, age, race, ethnicity, Charlson Comorbidity Index, community-wellbeing index, data partners, month of COVID-19 index date, main and interaction of vaccination) |
| Dryden-Peterson et al,37 2023 (USA) | Jan 1-Jul 17, 2022 | NIH (outpatients) | 44,551 | 1,2541 (not reported), 42 | 96 | 32,010 (not reported), 39 | 91 | Hospitalization at 14 days; death at 28 days; hospitalization or death (age, comorbidity score, vaccination status, recency of last vaccine dose, self-reported race and ethnicity, study period, neighborhood disadvantage of participant cohort census block groups) |
| Ganatra et al,38 2023 (USA) | Dec 1, 2021-Apr 18, 2022 | Not funded (outpatients) | 2,260 | 1,130 (57.5 ± 16.3), 37 | Not reported | 1,130 (57.7 ± 16.3), 35.9 | Not reported | Hospitalization or death at 30 days (not clear) |
| Lewnard et al,39 2023 (USA) | Apr 8-Oct 7, 2022 | CDC and NIH (outpatients) | 133,426 | 7,274 (not reported), 42.3 | 94.6 | 126,152 (not reported), 44.7 | 86.7 | Hospitalization or death at 30 days (age, sex, Charlson Comorbidity Index, history of vaccination and SARS-CoV-2 infection, race, body mass index, cigarette smoking, neighborhood socioeconomic status) |
| Najjar-Debbiny et al,40 2023 (Israel) | Jan-Feb 2022 | Not reported (outpatients) | 180,351 | 4,737 (68.5 ± 12.5), 42.1 | Not reported | 175,614 (53.9 ± 16.8), 44.7 | Not reported | Hospitalization or death at 28 days (age, population sector, socioeconomic status, body mass index, diabetes, hypertension, cardiovascular disease, chronic liver, lung, or kidney disease, neurologic disease, malignancy in the prior year, immunosuppression, COVID-19 vaccination status) |
| Paraskevis et al,41a 2023 (Greece) | Feb-Jul 2022 | Not funded (outpatients) | 26,190 | 13,462 (not reported), 48.1 | 90.5 | 12,728 (not reported), 46.6 | 85 | Hospitalization at 10 days, death at 35 days (age, previous SARS-CoV-2 infection, vaccination status, vaccination recency) |
| Park et al,42 2022 (South Korea) | Feb 6-Apr 2, 2022 | Not funded (not clear) | 819 | 623 (not reported), 48.6 | Not reported | 196 (not reported), 41.8 | Not reported | Hospitalization or death at 52 days, (sex, age, vaccination history, treatment history) |
| Schwartz et al,43 2023 (Canada) | Apr 4-Aug 31, 2022 | Public Health Ontario (outpatients) | 177,545 | 8,876 (74.3 ± 16.3), 40.7 | 94.7 | 168,669 (52.4 ±21.0), 36.6 | 93.8 | Hospitalization or death at 30 days (not clear) |
| Shah et al,44 2023 (USA) | Apr-Sep 2022 | Not reported (outpatients) | 699,848 | 198,927 (not reported), 38.2 | 84.6 | 500,921 (not reported), 36.8 | 71.7 | Hospitalization at 30 days (age, sex, race, ethnicity, social vulnerability index, number of underlying health conditions, US Census Bureau region of residence, previous infection, COVID-19 vaccination status excluding stratum of interest) |
| Wai et al,45 2023 (Hong Kong SAR, China) | Feb 22-Mar 31, 2022 | The Tung Foundation and AIR@InnoHK platform Hong Kong (outpatients) | 27,872 | 4,442 (not reported), 45.4 | Not reported | 23,430 (not reported), 47.3 | Not reported | Hospitalization or death at 28 days (age, sex, admitted from elderly homes, admitted through emergency department, constituent comorbidities of Charlson Comorbidity Index including acute myocardial infarction, congestive heart failure, peripheral vascular disease, cerebrovascular disease, dementia, COPD, rheumatoid disease, peptic ulcer disease, liver disease, diabetes with or without complications, hemiplegia or paraplegia, renal disease, cancer, metastatic cancer, HIV/AIDS) |
| Wong et al,46 2022 (Hong Kong SAR, China) | Feb 26-Jun 26, 2022 | Health and Medical Research Fund, Health Bureau, Government of Hong Kong (outpatients) | 60,214 | 5,542 (not reported), 46.3 | Not reported | 54,672 (not reported), 46.6 | Not reported | Hospitalization or death at 99 days (propensity score 1:10 according to age, sex, date of SARS-CoV-2 infection diagnosis, Charlson Comorbidity Index, vaccination status) |
| Yip et al,47 2023 (Hong Kong SAR, China) | Feb 16-Mar 31, 2022 | Not funded (outpatients) | 9,679 | 4,921 (70.8 ± 12.1), 45.7 | 42.6 | 4,758 (70.5 ± 12.2), 45.8 | 42.8 | Hospitalization at 30 days (not clear) |
| Zhou et al,48a 2022 (USA) | Dec 22, 2021-Jun 8, 2022 | Pfizer Inc (outpatients) | 13,657 | 2,808 (not reported), 42.1 | 67.6 | 10,849 (not reported), 41.8 | 66.4 | Hospitalization at 30 days (not clear) |
CDC = Centers for Disease Control and Prevention; COPD = chronic obstructive pulmonary disease; NIH = National Institutes of Health; SAR = Special Administrative Region; SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2; USA = United States of America.
↵a Unpublished data (available online but not peer reviewed).36,41,48