Post-Disease Divergence in SARS-CoV-2 RNA Detection between Nasopharyngeal, Anterior Nares and Saliva/Oral Fluid Specimens - Significant Implications for Policy & Public Health
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Abstract
Background
Patients have been shown to shed SARS-CoV-2 viral RNA in nasopharyngeal (NP) specimens for over 100 days after resolution of clinical disease (1, 2). How this relates to anterior nares and oral fluid specimens has not previously been investigated.
Methods
We prospectively collected oral fluid, anterior nares, NP swab and serum specimens from 1,326 individuals at 2 “drive-through” testing locations. The Curative SARS-CoV-2 Assay (Curative Assay)(3) on oral fluid and anterior nares specimens was compared to the EURORealTime SARS-CoV-2 Assay (EuroRT Assay)(4) on anterior nares and NP specimens. Viral culture and IgG serology were used to assess infectious potential and stage of disease.
Additionally we investigated differences in viral RNA detection between specimen types, both early (< 21 days) and late (> 21 days) in SARS-CoV-2 infection, by using an employee surveillance program with daily SARS-CoV-2 testing to precisely determine infection date, even without symptoms. We prospectively collected oral fluid, anterior nares and NP swab specimens from 165 subjects with early infections and 22 subjects with late infections. Specimens were tested using the Curative Assay with the “high-sensitivity” Hologic Aptima SARS-CoV-2 Assay (Hologic Assay)(5) on an NP swab used as the comparator. Late infection specimens were also tested with EuroRT and Zymo Quick SARS-CoV-2 rRT-PCR Kit (Zymo) (6) Assays.
Results
The “drive-through” study showed similar sensitivities of oral fluid and anterior nares specimens on the Curative Assay to anterior nares specimens tested with the EuroRT Assay. However NP specimens tested with the same EuroRT assay produced 20-30% more positives. Incorporating viral culture and serology data to exclude NP RT-PCR positives that are not infectious or late in the course of disease showed a Positive Percent Agreement (PPA) for of 98.2% and 96.2% and Negative Percent Agreement (NPA) of 97.6% and 98.1% for anterior nares and oral fluid specimens, respectively.
Within 21 days of infection, the Curative Assay showed a PPA and NPA of 100% and 100%, respectively for oral fluid; of 100% and 99% respectively for anterior nares; and of 98.2% and 99.0%, respectively in nasopharyngeal specimens compared to an NP specimen on the Hologic Assay. 29 positives were asymptomatic and showed 100% PPA and 100% NPA for all specimen types. After 21 days from infection onset, significant divergence between NP and other specimen types occurred on all 4 assays. Out of 22 paired sample sets, 18, 13, 8 and 4 NP specimens were positive on the Curative, Zymo, Hologic and EuroRT assays, respectively, compared to only 3, 2, 0 and 1 positive anterior nares specimens. Only one oral fluid sample was positive in both the Curative and Zymo assays.
Conclusions
We used a unique population to show significant divergence between NP specimens and anterior nares or oral fluid specimens >21 days from SARS-CoV-2 infection, which appears to be biological variation and is independent of assay used. This has significant public health implications for the use of NP specimens in community testing programs and policy implications for evaluation of novel specimen types and tests where the use of NP swabs as a comparator may say more about the study population than the assay or specimen type to be evaluated and may unnecessarily limit access to testing.
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SciScore for 10.1101/2021.01.26.21250523: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Limitations of Studies: The studies presented here were conducted predominantly in groups of mild to moderate severity COVID-19 cases and no hospitalized patients were included in the group. Although many studies recruited in …
SciScore for 10.1101/2021.01.26.21250523: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Sex as a biological variable not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Limitations of Studies: The studies presented here were conducted predominantly in groups of mild to moderate severity COVID-19 cases and no hospitalized patients were included in the group. Although many studies recruited in academic medical centers for SARS-CoV-2 have introduced the opposite bias and understanding, testing and disease progression in an outpatient setting is vital for managing the SARS-CoV-2 pandemic, there may be differences in the effects described here in severe COVID-19 cases requiring treatment and hospitalization as they were not included in the present study. Additionally the extensibility of these data to children under the age of 16 is unknown. Previous surveillance test data, which is performed with either oral fluid or anterior nares specimens on the Curative Assay, was used to recruit suspected positive subjects to the study. The possibility of a sampling bias here is reduced by the high frequency at which this employee surveillance testing was conducted (daily or twice-daily) and by the large suspected negative group which was recruited from the same population using the same criteria, except without the recent positive test result. The current prevalence of SARS-CoV-2 in Los Angeles, CA, Austin, TX and Washington, DC, where these studies were conducted, is very high and in the eligible study population is ∼3-4%. Therefore, if true positive cases were being missed by the surveillance testing that would have been caught on the reference test, we ...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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