Table 4.
Serology Test Result According to Symptoms and Use of Health Services Since the End of February 2020, Stratified by Type of Participant
| Index Cases (n = 219) | Household Members (n = 302) | Close Contacts Outside the Household (n = 69) | |||||
|---|---|---|---|---|---|---|---|
| No. (%) Seropositive | No. (%) Seropositive | Odds Ratio [95% CI] | P Value | No. (%) Seropositive | Odds Ratio [95% CI] | P Value | |
| Symptoms | |||||||
| Flu-like episodes | .000 | .008 | |||||
| 0 | 25/26 (96.2) | 34/117 (29.1) | Reference | 2/39 (5.1) | Reference | ||
| ≥1 | 190/193 (98.5) | 125/184 (67.9) | 3.55 [2.37–5.32] | 10/29 (34.5) | 8.64 [1.77–42.12] | ||
| Cough | .001 | .003 | |||||
| No | 58/58 (100.0) | 84/192 (43.8) | Reference | 5/53 (9.4) | Reference | ||
| Yes | 157/161 (97.5) | 76/110 (69.1) | 2.07 [1.36–3.15] | 7/16 (43.8) | 7.76 [2.02–29.84] | ||
| Runny or stuffy nose, sneezing | .001 | .008 | |||||
| No | 105/107 (98.1) | 93/208 (44.7) | Reference | 5/52 (9.6) | Reference | ||
| Yes | 110/112 (98.2) | 67/94 (71.3) | 2.18 [1.38–3.44] | 7/17 (41.2) | 6.33 [1.64–24.46] | ||
| Sore throat | .049 | .729 | |||||
| No | 137/140 (97.9) | 109/224 (48.7) | Reference | 8/52 (15.4) | Reference | ||
| Yes | 78/79 (98.7) | 51/78 (65.4) | 1.53 [1.00–2.33] | 4/17 (23.5) | 1.27 [0.33–4.84] | ||
| Dyspnea | .000 | .203 | |||||
| No | 123/125 (98.4) | 108/235 (46.0) | Reference | 9/61 (14.8) | Reference | ||
| Yes | 92/94 (97.9) | 52/67 (77.6) | 2.86 [1.74–4.70] | 3/8 (37.5) | 2.82 [0.57–13.97] | ||
| Feeling of fever | .000 | .901 | |||||
| No | 93/95 (97.9) | 87/206 (42.2) | Reference | 9/54 (16.7) | Reference | ||
| Yes | 122/124 (98.4) | 73/96 (76.0) | 2.74 [1.71–4.40] | 3/15 (20.0) | 1.09 [0.27–4.44] | ||
| Temperature ≥37.5°C (measured) | .000 | .007 | |||||
| No | 80/82 (97.6) | 82/209 (39.2) | Reference | 8/63 (12.7) | Reference | ||
| Yes | 135/137 (98.5) | 78/93 (83.9) | 4.64 [2.82–7.65] | 4/6 (66.7) | 12.61 [1.98–80.32] | ||
| Headache | .000 | .001 | |||||
| No | 79/81 (97.5) | 76/180 (42.2) | Reference | 4/52 (7.7) | Reference | ||
| Yes | 136/138 (98.6) | 84/122 (68.9) | 2.14 [1.43–3.19] | 8/17 (47.1) | 10.29 [2.55–41.62] | ||
| Pain in muscles, joints | .000 | .940 | |||||
| No | 86/89 (96.6) | 88/203 (43.4) | Reference | 10/58 (17.2) | Reference | ||
| Yes | 129/130 (99.2) | 72/99 (72.7) | 2.44 [1.61–3.70] | 2/11 (18.2) | 0.94 [0.18–4.84] | ||
| Chest pain | .444 | .018 | |||||
| No | 150/152 (98.7) | 131/258 (50.8) | Reference | 7/58 (12.1) | Reference | ||
| Yes | 65/67 (97.0) | 29/44 (65.9) | 1.23 [0.72–2.09] | 5/11 (45.5) | 5.56 [1.34–23.07] | ||
| Tiredness, exhaustion | .000 | .001 | |||||
| No | 31/33 (93.9) | 62/162 (38.3) | Reference | 3/49 (6.1) | Reference | ||
| Yes | 184/186 (98.9) | 98/140 (70.0) | 2.66 [1.79–3.95] | 9/20 (45.0) | 11.03 [2.64–45.97] | ||
| Appetite loss | .000 | .003 | |||||
| No | 89/93 (95.7) | 104/237 (43.9) | Reference | 7/61 (11.5) | Reference | ||
| Yes | 126/126 (100.0) | 56/65 (86.2) | 4.52 [2.50–8.17] | 5/8 (62.5) | 11.30 [2.28–55.89] | ||
| Nausea, vomiting | .004 | .181 | |||||
| No | 178/182 (97.8) | 138/275 (50.2) | Reference | 11/67 (16.4) | Reference | ||
| Yes | 37/37 (100.0) | 22/27 (81.5) | 2.93 [1.40–6.13] | 1/2 (50.0) | 6.51 [0.42–101.56] | ||
| Diarrhea | .001 | .475 | |||||
| No | 154/157 (98.1) | 123/250 (49.2) | Reference | 10/62 (16.1) | Reference | ||
| Yes | 61/62 (98.4) | 37/52 (71.2) | 2.37 [1.41–3.99] | 2/7 (28.6) | 1.90 [0.33–11.00] | ||
| Belly pain | .002 | .530 | |||||
| No | 175/178 (98.3) | 134/267 (50.2) | Reference | 10/62 (16.1) | Reference | ||
| Yes | 40/41 (97.6) | 26/35 (74.3) | 2.76 [1.44–5.28] | 2/7 (28.6) | 1.75 [0.31–10.01] | ||
| Sudden loss of smell or taste | .000 | .001 | |||||
| No | 74/77 (96.1) | 96/233 (41.2) | Reference | 6/62 (9.7) | Reference | ||
| Yes | 141/142 (99.3) | 64/69 (92.8) | 6.24 [3.46–11.24] | 6/7 (85.7) | 65.25 [5.47–779.10] | ||
| Use of health services | |||||||
| Contact with a medical provider | .000 | .027 | |||||
| No | 28/28 (100.0) | 86/209 (41.2) | Reference | 7/57 (12.3) | Reference | ||
| Yes | 185/189 (97.9) | 74/93 (79.6) | 3.61 [2.19–5.95] | 5/12 (41.7) | 4.62 [1.20–17.86] | ||
| Nasal or throat swabbing to detect SARS-CoV-2 | .000 | .002 | |||||
| No | (a) | 110/240 (45.8) | Reference | 7/63 (11.1) | Reference | ||
| Yes | (a) | 50/62 (80.7) | 2.74 [1.61–4.65] | 5/6 (83.3) | 38.52 [3.95–375.53] | ||
| Test result for SARS-CoV-2b | |||||||
| Negative or unknown | (a) | 5/16 (31.3) | ·· | 4/5 (80.0) | ·· | ||
| Positive | (a) | 45/46 (97.8) | ·· | 1/1 (100.0) | ·· | ||
| Hospitalization | .028 | ·· | |||||
| No | 181/185 (97.8) | 150/291 (51.6) | Reference | 11/68 (16.2) | ·· | ||
| Yes | 32/32 (100.0) | 10/11 (90.9) | 4.96 [1.19–20.62] | 1/1 (100.0) | ·· | ||
| Admission to the ICU | ·· | ·· | |||||
| No | 203/207 (98.1) | 158/300 (52.7) | ·· | 12/69 (17.4) | ·· | ||
| Yes | 10/10 (100.0) | 2/2 (100.0) | ·· | No participant | ·· | ||
| Intubation | ·· | ·· | |||||
| No | 210/214 (98.1) | 160/302 (53.0) | ·· | 12/69 (17.4) | ·· | ||
| Yes | 3/3 (100.0) | No participant | ·· | No participant | ·· | ||
All participants, including children and teens. Calculation of odds ratio and P value: correlation between close contacts of the same index case taken into account using GEEs (exchangeable correlation structure, logit link function).
Abbreviations: GEEs, generalized estimating equations; ICU, intensive care unit; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.
aIndex cases all tested positive.
bNucleic acid amplification test.