Table 1.
Comparison of studies assessing the effect of SARS-CoV-2 VOC on disease severity and clinical outcomes.
| The first author (reference) | Variant type | Patient recruitment | Study dates | Number of participants | Age of participants, years | Primary outcome | Rate of Severe disease | Rate of mortality | Effect on severe disease | Effect on mortality |
|---|---|---|---|---|---|---|---|---|---|---|
| Frampton et al. (25) | Alpha | Hospital patients with confirmed COVID-19 | November 9 to December 20, 2020 | 341 (69%) included of 496 available patients screened | Median 60 (IQR: 47–75) | Clinical severity as defined by WHO ordinal scale ≥6; mortality at 28 days | 0.369 | 0.162 | HR: 1.02 (95% CI: 0.76–1.38) | HR: 1.12 (95% CI 0.71–1.78) |
| Challen et al. (26) | Alpha | Public health data from community-based testing dataset | Oct 1, 2020, to Jan 28, 2021 | 109,812 (11.6%) included of 941,518 available patients screened | Mean 46.3 (SD 11.0) | Mortality at 28 days | NA | 0.003 | NA | HR: 1.64 (95% CI: 1.32–2.04) |
| Davies et al. (27) | Alpha | Public health data from community-based testing dataset | November 1, 2020 to January 23, 2021 | 1,146,534 (51.1%) included of 2,245,263 available patients screened | 1–34 (44.8%); 35–54 (35.2%); 55–69 (15.3%); 70–84 (3.8%); ≥85 (0.8%) | Mortality at 28 days | NA | 0.009 | NA | HR: 1.55 (95% CI: 1.39–1.72) |
| Grint et al. (28) | Alpha | Public health data from community and hospital-based testing dataset | November 16, 2020 to January 11, 2021 | 184,786 (41.9%) included of 441,161 available patients screened | Median 38.0 (IQR: 24.0–52.0); mean 38.2 (SD: 18.1) | Mortality at 28 days | NA | 0.005 | NA | HR: 1.67 (95% CI: 1.34–2.09) |
| Patone et al. (29) | Alpha | Public health data from community-based testing dataset | November 1, 2020 to 26 January, 2021 | 80,494 (40.6%) included of 198,420 available patients screened | NA | Clinical severity reported by being admitted to CCU: Mortality at 28 days |
NA | 0.008 | HR: 1.99 (95% CI: 1.59, 2.49) | HR: 1.59 (1.25–2.03) |
| Loconsole et al. (30) | Alpha | Public health data from community-based testing dataset | December 2020 to March 2021 | 621 (20.2%) included of 3,075 available patients screened | 0–4 (3.38%); 5–16 (12.08%);17–35 (23.19%);36–65 (43.8%); >65 (17.55%) |
Clinical severity reported by being admitted to Hospital, as severe; Mortality reported |
Hospital: 5.6%; Severe: 6.5% |
0.6% | HR Hospital: 2; Severe: 1.27 |
HR: 0.67 |
| Funk et al. (31) | Alpha and Beta and Gamma | Public health data from community-based testing dataset | October 2020 to March 2021 | 23,343 (0.7%) included of 3,200,000 available patients screened | Alpha: Mean 39 (SD: 21); Beta: Mean 43 (SD: 22); Gamma: Mean 46 (SD: 25); |
Clinical severity reported by being admitted to Hospital, being admitted to ICU; Mortality reported |
Hospital: 11% (Alpha); 19.3% (Beta); 20% (Gamma); ICU: 1.4% (Alpha); 2.3% (Beta); 2.1% (Gamma) | 0.02 (Alpha); 0.052 (Beta); 0.039 (Gamma) | HR Hospital (Alpha): 1.7 (95% CI: 1.0–2.9), (Beta): 3.6 (95% CI: 2.1–6.2); (Gamma): 2.6 (95% CI: 1.4–4.8); ICU (Alpha): 2.3 (95% CI: 1.4–3.5); (Beta): 3.3 (95% CI: 1.9–5.7); (Gamma): 2.2 (95% CI: 1.8–2.9) |
HR (Alpha): 0.5 (95% CI: 0.3–0.9), (Beta): 1.1 (95% CI: 0.4–3.4), (Gamma): 0.6 (95% CI: 0.3–1.0) |
| Public Health England (32) | Alpha and Delta | Public health data from community-based testing dataset |
March, 2021 to May, 2021 | 38,805 | NA | Clinical severity reported by being admitted to Hospital, being admitted to emergency care attendance or hospitalization | NA | NA | HR Hospital (Delta vs. Alpha): 2.61, (95% CI: 1.56–4.36); care attendance or hospitalization (Delta vs. Alpha): 1.67, (95% CI: 1.25–2.23) |
NA |
| Bager et al. (33) | Alpha | Public health data from community-based testing dataset |
January 1 to March 24, 2021 | 10,544 (20.7%) included of 50,958 available patients screened | 0–29 (44.4%) 30–59 (44.3%) ≥60 (11.3%) | Clinical severity reported by being admitted to hospital; Mortality reported | 0.054 | NA | HR Hospital: 1.42 (95% CI: 1.25–1.60) |
NA |
| Cetin et al. (34) | Alpha | Public health data from community-based testing dataset |
April 2020 to March 2021 | 588 (15.9%) included of 3,707 available patients screened | NA | Clinical severity reported by being admitted to hospital, being admitted to ICU; Mortality reported | Hospital: 0.335, ICU: 0.075 | NA | HR Hospital: 2.62; ICU: 1.923 |
NA |
| Fisman and Tuite (35) | Alpha and Beta and Gamma and Delta | Public health data from community-based testing dataset |
February 7 to June 27, 2021 | 168,909 (65.47%) included of 257,997 available patients screened | NA | Clinical severity reported by being admitted to hospital, being admitted to ICU; Mortality reported | Hospital (Alpha and Beta and Gamma): 0.054, ICU (Alpha and Beta and Gamma): 0.012; Hospital (Delta): 0.058, ICU (Delta): 0.015 | 0.009 (Alpha and Beta and Gamma); 0.007 (Delta) | HR Hospital (Alpha and Beta and Gamma): 1.52 (95% CI: 1.42–1.63); (Delta): 2.08 (95% CI: 1.78–2.4); ICU (Alpha and Beta and Gamma): 1.89 (95% CI: 1.67–2.17); (Delta): 3.35 (95% CI: 2.6–4.3) |
HR (Alpha and Beta and Gamma): 1.51 (95% CI: 1.3–1.78); (Delta): 2.33 (95% CI: 1.54–3.31) |
| Freitas et al. (36) | Gamma | Public health data from community-based testing dataset |
April 1, 2020 to May 31, 2021 and January 1 to January 31, 2021 |
6,142 (47.4%) included of 12,958 available patients screened | NA | Clinical severity reported by being admitted to hospital; Mortality reported | Hospital: 0.860 | 0.597 | HR Hospital: 0.914 |
HR: 1.315 |
| Grint et al. (37) | Alpha | Public health data from community-based testing dataset |
November 16, 2020 to April 21, 2021 | 93,153 (50.29%) included of 185,234 available patients screened | NA | Clinical severity reported by being admitted to hospital; Mortality reported | 0.015 | 0.0027 | HR: 1.62 (95% CI: 1.48 −1.78) | HR: 1.73 (95% CI: 1.41–2.13) |
| Giles et al. (38) | Alpha | Hospitalized patients with confirmed COVID-19 | NA | 30 (50%) included of 60 available patients screened | NA | Clinical severity as defined by WHO ordinal scale ≥ 6; mortality at 28 day | 0.37 | 0.321 | HR: 1.37 | HR: 1.551 |
| Hoang et al. (39) | Alpha and Beta and Gamma | Hospitalized patients with confirmed COVID-19 | February–May 2020, June–December 2020, January –September 2021 | 935 (53.16%) included of 1,760 available patients screened | NA | Clinical severity reported by being admitted to hospital, being admitted to ICU; Mortality reported | Hospital (Alpha): 0.249, (Beta): 0.316, (Gamma): 0.2; ICU (Alpha): 0.071, (Beta): 0.092, (Gamma): 0.1 | (Alpha): 0.042, (Beta): 0, (Gamma): 0 | HR Hospital (Beta vs. Alpha): 1.27, (Gamma vs. Beta): 0.633, (Gamma vs. Alpha): 0.833; ICU (Beta vs. Alpha): 1.314, (Gamma vs. Beta): 1.087, (Gamma vs. Alpha): 1.314 |
NA |
| Kim et al. (40) | Alpha | Public health data from community-based testing dataset | September 20 to December 15, 2020 | 1,769 (50%) included of 3,538 available patients screened | NA | Clinical severity reported by being admitted to hospital; Mortality reported | Hospital: 0.009 | 0.0089 | HR: 0.6 | HR: 1.22 |
| Meyer et al. (41) | Alpha | Public health data from community-based testing dataset | January 12 to June 3, 2021 | 59 (1.66%) included of 3,544 available patients screened | Minimum 0.0 years, maximum 17.8 years | Clinical severity reported by being admitted to hospital, being admitted to ICU | Hospital: 0.153; ICU: 0.017 | NA | HR Hospital: 1.89; ICU: NA |
NA |
| Ong et al. (42) | Alpha, Beta, and Delta | The Ministry of Health | January 1 to May 22, 2021 | 829 (85%) included of 976 available patients screened | NA | Clinical severity reported by being admitted to ICU: Mortality reported | NA | NA | HR (Delta VS wild-type); ICU: 1.88 (95% CI: 0.95–3.76); others No significant difference | HR (Delta vs. wild-type): 1.88 (95% CI: 0.95–3.76); others No significant difference |
| Martínez-García et al. (43) | Alpha | Hospital patients with confirmed COVID-19 | January 2 to April 30, 2021 | 426 (27.4%) included of 1,555 available patients screened | NA | Clinical severity reported by being admitted to ICU; Mortality reported | 19.5% | 13.9% | HR ICU: 2.11 (95% CI: 1.55 −2.87) |
HR: 0.87 (95% CI: 0.62–1.23) |
| Yilmaz et al. (44) | Alpha | Public health data from community-based testing Data set |
February 2 to February 9, 2021 | 339 (26.1%) included of 1,300 available patients screened | NA | Clinical severity reported by being admitted to Hospital; in intensive care |
Hospital: 3.2%, intensive care: 0.58% | NA | HR Hospital: 47.76%; intensive care: 77.78% |
NA |
| Twohig et al. (45) | Alpha, Delta | The Ministry of Health | January 1 to May 22, 2021 | 829 (85%) included of 976 available patients screened | NA | Clinical severity reported by being admitted to ICU; Mortality reported | Hospital: 2.3%, emergency care: 3.4% | NA | HR Hospital (Delta vs. Alpha): 2.26 (95% CI: 1.32–3.89); emergency care: 1.7 |
NA |
| Veneti et al. (46) | Alpha, Beta | Norwegian Surveillance System for Communicable Diseases | December 28 to May 2, 2021 | 23,717 (83.8%) included of 28,301 available patients screened | NA | Clinical severity reported by being admitted to hospital, being admitted to ICU | Hospital (Alpha): 3.8%, (Beta): 4.2%, ICU (Alpha): 0.8%, (Beta): 0.9% | NA | HR Hospital (Alpha vs. wild-type): 1.9 (95% CI: 1.6–2.3), (Beta vs. wild-type): 2.4 (95% CI: 1.7–3.3); ICU (Alpha vs. wild-type): 1.8 (95% CI: 1.2–2.8), (Beta vs. wild-type): 2.7 (95% CI: 1.2–6.5) |
NA |
| Patone et al. (47) | Alpha | Public health data from community-based testing Data set |
November 1, 2020 to January 27, 2021 | 117,926 (59.4%) included of 198,420 available patients screened | NA | Clinical severity reported by being admitted to CCU; mortality at 28 day | CCU: 0.4% | 0.4% | HR CCU: 2.15 (95% CI: 1.75–2.65) |
HR 1.65 (95% CI: 1.36–2.01) |
| Nyberg et al. (48) | Alpha | Public health data from community-based testing | November 1, 2020 to January 27, 2021 | 592,409 (70.59%) included of 839,278 available patients screened | NA | Clinical severity reported by being admitted to Hospital; mortality at 28 day | Hospital: 4.7% | 0.44% | HR Hospital: 1.52 (95% CI: 1.47–1.57) |
HR: 1.59 (95% CI: 1.44–1.74) |
| Stirrup et al. (49) | Alpha | Hospital patients with confirmed COVID-19 | November 16, 2020 to January 10, 2021 | 1,107 (47.29%) included of 2,341 available patients screened | NA | Clinical severity reported by being admitted to ITU; mortality at 28 day | ITU: 20.35% | 19.62% | HR ITU: 1.01 (95% CI: 0.75–1.37) |
HR: 1.01 (95% CI: 0.79–1.28) |
| Whittaker et al. (50) | Alpha | Public health data from community-based testing Data set |
December 21, 2020 to April 25, 2021 | 946 (81%) included of 1,186 available patients screened | NA | Clinical severity reported by being admitted to ICU; Died in hospital | ICU: 18% | 6% | HR ICU: 1.125 |
HR: 1 |