tetano
Editor, Senior Moderator
Open Forum Infect Dis
. 2021 Jan 28;8(4)
fab039.
doi: 10.1093/ofid/ofab039. eCollection 2021 Apr.
Performance of Unobserved Self-Collected Nasal Swabs for Detection of SARS-CoV-2 by RT-PCR Utilizing a Remote Specimen Collection Strategy
Ron M Kagan[SUP] 1 [/SUP], Amy A Rogers[SUP] 1 [/SUP], Gwynngelle A Borillo[SUP] 1 [/SUP], Nigel J Clarke[SUP] 2 [/SUP], Elizabeth M Marlowe[SUP] 1 [/SUP]
Affiliations
Abstract
Background: The use of a remote specimen collection strategy employing a kit designed for unobserved self-collection for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) can decrease the use of personal protective equipment (PPE) and exposure risk. To assess the impact of unobserved specimen self-collection on test performance, we examined results from a SARS-CoV-2 qualitative RT-PCR test for self-collected specimens from participants in a return-to-work screening program and assessed the impact of a pooled testing strategy in this cohort.
Methods: Self-collected anterior nasal swabs from employee return-to-work programs were tested using the Quest Diagnostics Emergency Use Authorization SARS-CoV-2 RT-PCR. The cycle threshold (Ct) values for the N1 and N3 N-gene targets and a human RNase P (RP) gene control target were tabulated. For comparison, we utilized Ct values from a cohort of health care provider-collected specimens from patients with and without coronavirus disease 2019 symptoms.
Results: Among 47923 participants, 1.8% were positive. RP failed to amplify for 13/115435 (0.011%) specimens. The median (interquartile range) Cts were 32.7 (25.0-35.7) for N1 and 31.3 (23.8-34.2) for N3. Median Ct values in the self-collected cohort were significantly higher than those of symptomatic but not asymptomatic patients. Based on Ct values, pooled testing with 4 specimens would have yielded inconclusive results in 67/1268 (5.2%) specimens but only a single false-negative result.
Conclusions: Unobserved self-collection of nasal swabs provides adequate sampling for SARS-CoV-2 RT-PCR testing. These findings alleviate concerns of increased false negatives in this context. Specimen pooling could be used for this population, as the likelihood of false-negative results is very low when using a sensitive, dual-target methodology.
Keywords: COVID-19; RT-PCR; SARS-CoV-2; cycle threshold; self-collection.
. 2021 Jan 28;8(4)
fab039.doi: 10.1093/ofid/ofab039. eCollection 2021 Apr.
Performance of Unobserved Self-Collected Nasal Swabs for Detection of SARS-CoV-2 by RT-PCR Utilizing a Remote Specimen Collection Strategy
Ron M Kagan[SUP] 1 [/SUP], Amy A Rogers[SUP] 1 [/SUP], Gwynngelle A Borillo[SUP] 1 [/SUP], Nigel J Clarke[SUP] 2 [/SUP], Elizabeth M Marlowe[SUP] 1 [/SUP]
Affiliations
- PMID: 33954224
- PMCID: PMC7928651
- DOI: 10.1093/ofid/ofab039
Abstract
Background: The use of a remote specimen collection strategy employing a kit designed for unobserved self-collection for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) can decrease the use of personal protective equipment (PPE) and exposure risk. To assess the impact of unobserved specimen self-collection on test performance, we examined results from a SARS-CoV-2 qualitative RT-PCR test for self-collected specimens from participants in a return-to-work screening program and assessed the impact of a pooled testing strategy in this cohort.
Methods: Self-collected anterior nasal swabs from employee return-to-work programs were tested using the Quest Diagnostics Emergency Use Authorization SARS-CoV-2 RT-PCR. The cycle threshold (Ct) values for the N1 and N3 N-gene targets and a human RNase P (RP) gene control target were tabulated. For comparison, we utilized Ct values from a cohort of health care provider-collected specimens from patients with and without coronavirus disease 2019 symptoms.
Results: Among 47923 participants, 1.8% were positive. RP failed to amplify for 13/115435 (0.011%) specimens. The median (interquartile range) Cts were 32.7 (25.0-35.7) for N1 and 31.3 (23.8-34.2) for N3. Median Ct values in the self-collected cohort were significantly higher than those of symptomatic but not asymptomatic patients. Based on Ct values, pooled testing with 4 specimens would have yielded inconclusive results in 67/1268 (5.2%) specimens but only a single false-negative result.
Conclusions: Unobserved self-collection of nasal swabs provides adequate sampling for SARS-CoV-2 RT-PCR testing. These findings alleviate concerns of increased false negatives in this context. Specimen pooling could be used for this population, as the likelihood of false-negative results is very low when using a sensitive, dual-target methodology.
Keywords: COVID-19; RT-PCR; SARS-CoV-2; cycle threshold; self-collection.