High anal swab viral load predisposes adverse clinical outcomes in severe COVID-19 patients

Figures & data

Table 1. The demographic information and clinical symptoms of recruited COVID-19 patients.

	Total (cases = 188)	Survivors (cases = 147)	Non-survivors (cases = 41)	P value
Age, years
Median (IQR)*	57.5 (48.8-67.3)	56.0 (46.0-65.0)	65.0 (57.0-73.5)	<0.001
Sex, n (%)				0.198
Male	112 (59.6)	84 (57.1)	28 (68.3)	..
Female	76 (40.4)	63 (42.9)	13 (31.7)	..
Underlying disease, n (%)
Yes	111 (59.0)	88 (59.9)	23 (56.1)	0.665
Hypertension	65 (34.6)	53 (36.1)	12 (29.3)	0.419
Diabetes	23 (12.2)	20 (13.6)	3 (7.3)	0.277
Heart disease	15 (8.0)	11 (7.5)	4 (9.8)	0.744
Cerebrovascular disease	13 (6.9)	10 (6.8)	3 (7.3)	1.000
Chronic kidney disease	6 (3.2)	5 (3.4)	1 (2.4)	1.000
Malignancy	6 (3.2)	4 (2.7)	2 (4.9)	0.613
Chronic liver disease	8 (4.3)	6 (4.1)	3 (7.3)	0.412
Symptoms, n (%)
Fever	175 (93.1)	139 (94.6)	36 (87.8)	0.161
Cough	160 (85.1)	127 (86.4)	33 (80.5)	0.348
Fatigue	49 (26.1)	40 (27.2)	9 (22.0)	0.498
Headache	7 (3.7)	6 (4.1)	1 (2.4)	1.000
Muscle pain	22 (11.7)	19 (12.9)	3 (7.3)	0.418
Pharyngalgia	6 (3.2)	6 (4.1)	0 (0.0)	0.342
Dyspnea	23 (12.2)	18 (12.2)	5 (12.2)	0.993
Diarrohea	5 (2.7)	5 (3.4)	0 (0.0)	0.587
Severity on the seven-category ordinal scale, n (%)
3	26 (13.8)	21 (14.3)	5 (12.2)	0.732
4	134 (71.3)	106 (72.1)	28 (68.3)	0.633
5	28 (14.9)	20 (13.6)	8 (19.5)	0.348
Antibiotic use, n (%)				0.613
Yes	182 (96.8)	143 (97.3)	39 (95.1)	..
Corticosteroid use, n (%)				0.294
Yes	65 (34.6)	48 (32.7)	17 (41.5)	..

* IQR, interquartile range. P values were calculated by two-sided unpaired t-test or χ² test as appropriate.

Figure 1. Virus positive rates in throat swab (TS) and anal swab (AS) samples. (A) The time course of positive rates in TS and AS samples on each day after symptom onset is shown (left part). The average viral RNA positive rates in TS and AS samples shown in the column were compared (right part). (B) The weekly positive rates in TS and AS samples after symptom onset. (C) The virus positive rates in TS and AS samples in survivors and non-survivors. (D) The weekly positive rates in survivors and non-survivors.

Figure 2. The time to SARS-CoV-2 positivity in throat swab (TS) and anal swab (AS) samples. (A) The time from symptom onset to viral RNA positivity in TS and AS samples. (B) The time from symptom onset to viral RNA positivity in TS and AS samples from survivors and non-survivors. (C) The time to viral RNA negativity after a positive result in TS and AS samples. (D) The time to viral RNA negativity after a positive result in TS and AS samples from survivors and non-survivors.

Figure 3. Viral load dynamics in throat swab (TS) and anal swab (AS) samples from patients with COVID-19. (A) The viral load in serial samples collected every 4–7 days. (B) The weekly mean viral load in the specimens post symptom onset. (C) The viral loads in specimens from survivors and non-survivors. (D) The weekly mean viral loads in specimens from patients with different outcomes post symptom onset.

Table 2. Association between initial viral load and adverse outcomes of COVID-19 patients.

Outcome	Initial viral load^† (log10 copies/ml)	Unadjusted OR (95% CI)	P value	Adjusted^†† OR (95% CI)	P value
Death	TS	1.075 (0.936-1.235)	0.308	1.063 (0.891-1.268)	0.495
	AS	1.191 (1.002-1.415)	0.047	1.368 (1.076-1.741)	0.011
ICU	TS	0.960 (0.817-1.128)	0.622	0.938 (0.784-1.121)	0.481
	AS	1.204 (1.001-1.447)	0.049	1.237 (1.001-1.528)	0.049
IMV	TS	0.966 (0.815-1.146)	0.694	0.934 (0.773-1.128)	0.477
	AS	1.293 (1.071-1.562)	0.008	1.340 (1.076-1.669)	0.009

TS = Throat swab. AS = Anal swab. IMV = Invasive mechanical ventilation. ICU = Intensive care unit. OR = Odds ratio. † Initial viral loads in anal swab and throat swab samples were analysed. †† Results were adjusted based on age, severity on the seven-category ordinal scale, use of corticosteroids, use of lopinavir-ritonavir and days from symptom onset to enrolment.