Table 2 Estimated effectiveness of one and two doses of vaccination (all or primarily tozinameran) to prevent diagnosed cases, hospitalized cases and deaths from the present ecologic study in Costa Rica and from other selected studies
References | Location | Dates covered | Doses | Comments | Incident cases | Hospitalizations | Deaths |
|---|---|---|---|---|---|---|---|
Current study | Costa Rica | 12/1/2020–5/13/2021 | 1 | Ecologic study design. Primarily Alpha (B1.1.7) variant | 59% (53 to 64)a | 76% (68 to 85) | 63% (47 to 80) |
2 | 93% (90 to 96)a | 100% (97 to 100) | 100% (97 to 100) | ||||
Haas et al. [3] | Israel | 1/24/2021–4/3/2021 | 2 | Observational cohort study. Primarily Alpha variant | 97∙0% (96∙7 to 97∙2)b | 97∙2% (96.8 to 97.5) | 96∙7% (96.0 to 97.3) |
Chung et al. [6] | Ontario, Canada | 12/14/2020–4/19/2021 | 1 | Community-based test-negative case–control design. Alpha variant primarily | 59% (55 to 62)b | NA | 69% (59–77)f |
2 | 91% (88 to 93)b | NA | 96% (82–99)f | ||||
Polack et al. [2] | Multinational, primarily US | 7/27/2020–11/14/2020 | 2 | Randomised, double-blinded trial. Probably the Alpha variant | 94∙6% (89.9 to 97.3)b | NA | NA |
Chemaitelly et al. [5] | Qatar | 1/1/2021–9/5/2021 | 1 | Test-negative case–control design. Beta and Delta variants | 36∙8% (33.2 to 40.2)c | NA | NA |
2 | 77∙5% (76.4 to 78.6)c | NA | NA | ||||
Tang et al. [4] | Qatar | 3/23/2021–9/7/2021 | 1 | Test-negative case–control design against Delta variant | 45.3% (22.0 to 61.6)c | NA | 79∙7% (− 59.5 to 97.4)d |
2 | 51.9% (47.0 to 56.4)c | NA | 93∙4% (85.4 to 97.0)d | ||||
Tenforde et al. [7] | United States | 3/11/2021–8/15/2021 | 2 | Hospital-based case–control. Alpha and Delta variants | NA | 85% (82 to 87) | NAe |