Table 3.
Multivariable logistic regression analysis evaluating the association between SARS-CoV-2 variant/lineage and severe disease among hospitalised individuals, South Africa, 1 October 2021 – 26 April 2022a (N = 3574)
| Severe diseaseb n/N (%) | Odds ratio (95% CI) | Adjusted odds ratio (95% CI) | P value | ||
|---|---|---|---|---|---|
| SARS-CoV-2 variant/lineagec | N = 3825 | ||||
| Delta | 97/168 (58) | 2.69 (1.96–3.69) | 2.47 (1.73–3.52) | <0.001 | |
| BA.1 | 990/2940 (34) | Ref | Ref | - | |
| BA.2 | 167/637 (26) | 0.70 (0.58–0.85) | 0.78 (0.63–0.97) | 0.029 | |
| BA.4/BA.5 | 22/80 (28) | 0.75 (0.45–1.23) | 0.72 (0.41–1.26) | 0.252 | |
| Age group (years) | N = 3825 | ||||
| <5 | 45/267 (17) | 0.94 (0.57–1.54) | 1.03 (0.60–1.76) | 0.922 | |
| 5–12 | 11/137 (8) | 0.40 (0.20–0.83) | 0.48 (0.23–1.02) | 0.058 | |
| 13–18 | 18/134 (13) | 0.72 (0.38–1.34) | 0.81 (0.42–1.58) | 0.542 | |
| 19–24 | 32/180 (18) | Ref | Ref | – | |
| 25–39 | 188/976 (19) | 1.10 (0.73–1.67) | 1.06 (0.68–1.66) | 0.795 | |
| 40–59 | 351/968 (36) | 2.63 (1.76–3.94) | 2.57 (1.65–4.00) | <0.001 | |
| ≥60 | 631/1163 (54) | 5.49 (3.68–8.18) | 5.22 (3.37–8.08) | <0.001 | |
| Sex | N = 3808 | ||||
| Male | 600/1616 (37) | Ref | Ref | – | |
| Female | 669/2192 (31) | 0.74 (0.65–0.85) | 0.81 (0.69–0.94) | 0.007 | |
| Province | N = 3727 | ||||
| Eastern Cape | 1/4 (25) | 1.06 (0.11–10.56) | 2.48 (0.20–30.12) | 0.475 | |
| Free State | 43/99 (43) | 2.45 (1.42–4.23) | 3.80 (2.01–7.16) | <0.001 | |
| Gauteng | 650/1800 (36) | 1.81 (1.23–2.66) | 3.31 (2.10–5.21) | <0.001 | |
| KwaZulu-Natal | 322/1110 (29) | 1.31 (0.88–1.94) | 2.15 (1.34–3.43) | 0.001 | |
| Limpopo | 19/98 (19) | 0.77 (0.41–1.44) | 1.62 (0.79–3.30) | 0.188 | |
| Mpumalanga | 76/237 (32) | 1.51 (0.95–2.40) | 2.67 (1.53–4.64) | 0.001 | |
| North West | 51/189 (27) | 1.18 (0.72–1.93) | 2.46 (1.39–4.37) | 0.002 | |
| Northern Cape | 31/39 (79) | 12.38 (5.22–29.33) | 11.66 (4.59–29.61) | <0.001 | |
| Western Cape | 36/151 (24) | Ref | Ref | - | |
| Co-morbidityd | N = 3825 | ||||
| Absent | 772/2735 (28) | Ref | Ref | - | |
| Present | 504/1090 (46) | 2.19 (1.89–2.53) | 1.57 (1.32–1.87) | <0.001 | |
| Healthcare sector | N = 3825 | ||||
| Public | 559/1436 (39) | Ref | Ref | – | |
| Private | 717/2389 (30) | 0.67 (0.59–0.77) | 0.72 (0.60–0.86) | <0.001 | |
| Days between diagnosis and admission | N = 3673 | ||||
| 1–7 days before diagnosis | 129/340 (38) | Ref | Ref | - | |
| 0–6 days after diagnosis | 969/3023 (32) | 0.77 (0.61–0.97) | 0.84 (0.65–1.10) | 0.206 | |
| 7–21 days after diagnosis | 112/310 (36) | 0.93 (0.67–1.27) | 0.96 (0.67–1.38) | 0.826 | |
| SARS-CoV-2 vaccinatione | N = 3825 | ||||
| No | 403/1195 (34) | Ref | Ref | - | |
| Yes | 54/185 (29) | 0.81 (0.58–1.14) | 0.80 (0.54–1.17) | 0.250 | |
| Unknown | 819/2445 (34) | 0.99 (0.86–1.15) | 0.92 (0.77–1.09) | 0.339 |
aIndividuals followed-up for in-hospital outcome until 11 May 2022.
bSevere disease defined as a hospitalised patient meeting at least one of the following criteria: admitted to ICU, received oxygen treatment, ventilated, received extracorporeal membrane oxygenation (ECMO), experienced acute respiratory distress syndrome (ARDS) and/or died.
cSGTP infections diagnosed in October and November 2021 were classified as Delta, SGTF infections diagnosed between November 2021 through January 2022 were classified as BA.1, SGTP infections diagnosed from February through April 2022 were classified as BA.2 and SGTF infections diagnosed in April 2022 were classified as BA.4/BA.5.
dCo-morbidity defined as ≥1 of the following conditions: hypertension, diabetes, chronic cardiac disease, chronic kidney disease, asthma, chronic obstructive pulmonary disease (COPD), malignancy, HIV, and active or past tuberculosis.
eVaccination defined as at least one dose of Ad26.COV2.S or two doses of BNT162b.