Table 2

The frequencies of SARS-CoV-2 RNA positive, suspected-positive and negative samples.

AllSOCCPAPHFNO
Number of participants 30101010
Nasopharyngeal samples
Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only21/1/8 (73%) 29.2(27 to 32)8/1/1 (90%) 29.8(26 to 34)8/0/2 (80%) 31.2(27 to 35)5/0/5 (50%) 24.9(18 to 32)
Overall for air samples Number positive/suspected-positive/negative (overall % positive or suspected-positive)4/10/76 (16%)1/4/25 (17%)0/2/28 (7%)3/4/23 (23%)
Air samples collected with participant breathing normally (SOC or CPAP/HFNO off) Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only2/4/24 (20%) 38.2(35 to 41)1/2/7 (30%) 39.7(32 to 48)0/1/9 (10%) 37.3(-)1/1/8 (20%) 36.3(7 to 66)
Air samples collected with participant breathing normally (SOC or CPAP/HFNO on) Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only1/3/26 (13%) 39.0(34 to 44)0/1/9 (10%) 37.4(-)0/0/10 (0%) -(-)1/2/7 (30%) 39.6(31 to 48)
Air samples collected with participant coughing every 2 min (SOC or CPAP/HFNO on) Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI)for lowest Ct value for E or ORF1a only1/3/26 (13%) 38.6(35 to 42)0/1/9 (10%) 39.9(-)0/1/9 (10%) 39.9(-)1/1/8 (20%) 37.5(13 to 63)
Overall for surface samples Number positive/suspected-positive/negative (overall % positive or suspected-positive)6/10/74 (18%)1/4/25 (17%)3/3/24 (20%)2/3/25 (17%)
Floor surfaces Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only5/4/21 (30%) 37.3(36 to 48)1/1/8 (20%) 35.8(18 to 54)3/1/6 (40%) 36.8(36 to 38)1/2/7 (30%) 38.9(37 to 41)
Table surfaces Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only0/3/27 (10%) 39.0(36 to 42)0/2/8 (20%) 38.5(30 to 47)0/0/10 (0%) -(-)0/1/9 (10%) 40.0(-)
High-object surfaces Number positive/suspected-positive/negative (overall % positive or suspected-positive) Mean Ct value (95% CI) for lowest Ct value for E or ORF1a only1/3/26 (13%) 37.8(35 to 41)0/1/9 (10%) 39.4(-)0/2/8 (20%) 38.4(32 to 45)1/0/9 (10%) 34.8(-)
  • A Ct value<45 for both the SARS-CoV-2 E gene and ORF1a gene was considered a positive result. A suspected positive result was recorded when only E or ORF1a Ct values were <45. A negative result was recorded when both E and ORF1a Ct values were ≥45. Nasopharyngeal samples were collected according to local standard operating procedures and air samples and surfaces samples were collected per participant in accordance with the clinical study plan. There were no statistically significant differences in the Ct values of viral RNA in nasopharyngeal samples between study groups (p=NS, two-way ANOVA), and no statistically significant differences in the proportion of negative samples in each air and surface sample across the study groups (p=NS, Fisher’s exact test). Alternative statistical tables are available in the online supplemental material.

  • ANOVA, analysis of variance; CPAP, continuous positive airway pressure; Ct, cycle time; HFNO, high-flow nasal oxygen; SOC, supplemental oxygen care.