Table 1:
Factors associated with cumulative incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on real-time reverse transcription polymerase chain reaction (rRT-PCR) and/or serology in a rural and an urban community, South Africa, 2020–2021
| SARS-CoV-2 infection | Univariate | Multivariable | ||
|---|---|---|---|---|
| Variable | n/N (%) | RRe (95% CI) | aRRe (95% CI) | |
| Site | Rural | 368/643 (57) | Reference | Reference |
| Urban | 381/557 (68) | 1.9 (1.2–3.0) | 1.7 (1.1–2.7) | |
| Age group (years) | <5 | 75/154 (49) | Reference | Reference |
| 5–12 | 205/340 (60) | 2.0 (1.2–3.2) | 1.8 (1.1–2.9) | |
| 13–18 | 132/170 (78) | 5.1 (2.8–9.2) | 4.4 (2.4–8.1) | |
| 19–39 | 165/265 (62) | 1.9 (1.1–3.0) | 1.5 (0.9–2.6) | |
| 40–59 | 115/168 (68) | 2.7 (1.5–4.7) | 2.1 (0.9–4.2) | |
| ≥60 | 57/103 (55) | 1.5 (0.8–2.8) | 1.2 (0.6–2.4) | |
| Sex | Female | 454/717 (63) | 1.1 (0.8–1.5) | |
| Male | 295/483 (61) | Reference | ||
| HIV and viral load copies/mla | Uninfected | 608/971 (63) | Reference | |
| Infected <400 | 87/136 (64) | 1.1 (0.7–1.7) | ||
| Infected ≥400 | 22/31 (71) | 1.5 (0.6–3.8) | ||
| HIV and/or viral load unknown | 32/62 (52) | 0.5 (0.3–1.1) | ||
| HIV and CD4+ T cell count/mlb | Uninfected | 608/971 (63) | Reference | |
| Infected ≥200 | 99/151 (66) | 1.1 (0.7–1.7) | ||
| Infected <200 | 8/14 (57) | 1.0 (0.3–3.7) | ||
| HIV and/or CD4+ unknown | 34/64 (53) | 0.6 (0.3–1.2) | ||
| Other underlying illnessc | Absent | 672/1075 (63) | Reference | |
| Present | 77/125 (62) | 0.8 (0.5–1.3) | ||
| BMId | Underweight | 55/85 (65) | 1.3 (0.7–2.3) | 1.1 (0.6–2.1) |
| Normal weight | 371/642 (58) | Reference | Reference | |
| Overweight | 150/219 (68) | 1.7 (1.1–2.5) | 1.6 (1.1–2.6) | |
| Obese | 171/252 (68) | 1.5 (1.0–2.1) | 1.4 (0.9–2.2) | |
| Number of individuals in household | 3–5 | 311/511 (61) | Reference | |
| 6–10 | 369/571 (65) | 1.3 (0.8–2.1) | ||
| ≥11 | 69/118 (58) | 1.0 (0.3–2.9) | ||
| Crowding (>2 people/sleeping room) | No | 381/640 (60) | Reference | |
| Yes | 368/560 (66) | 1.5 (0.9–2.4) |
HIV – Human immunodeficiency virus, BMI – Body mass index, RR – relative risk
Additional variables evaluated but not found to be significant on univariate or multivariable analysis: use of alcohol, current or previous smoking, current or previous tuberculosis, household income, fuel used for cooking, main water source.
HIV data available for 1147 of 1200 (96%) individuals. Among 176 people living with HIV (PLHIV), 167 (95%) had available data on HIV viral load
Among 176 PLHIV, 165 (93%) had available data on CD4+ T cell count
Self-reported history of asthma, lung disease, heart disease, stroke, spinal cord injury, epilepsy, organ transplant, immunosuppressive therapy, organ transplantation, cancer, liver disease, renal disease or diabetes
BMI=body mass index calculated using the formula (weight in kilograms)/(height in metres squared). We defined BMI categories as follows: underweight - age <18 years weight for age or BMI <−2 standard deviations of the World Health Organization (WHO) Child Growth Standards, age ≥18 years BMI <18.5kg/m2; overweight - age <18 years BMI >+1 and ≤+2 standard deviations of the WHO growth standards, age ≥18 years BMI ≥25 and <30kg/m2, obese – age <18 years BMI >+2 standard deviations of the WHO growth standards, age ≥18 years BMI ≥30 kg/m2
Estimated using Poisson regression adjusted for clustering by site and household