High Rates of Rapid Antigen Test Positivity After 5 days of Isolation for COVID-19
This article has been Reviewed by the following groups
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- Evaluated articles (ScreenIT)
- Evaluated articles (Rapid Reviews Infectious Diseases)
Abstract
Background
The emergence of the highly transmissible COVID-19 variant, omicron, has resulted in high numbers of breakthrough infections, including among healthcare workers (HCW). Recent CDC recommendations now allow healthcare workers to return to work after day 5 if symptoms have improved, without a requirement for a negative rapid antigen test (RAT).
Methods
Fully vaccinated and non-immunocompromised HCW at a large, urban, academic medical center who tested positive for COVID-19 starting in late December, 2021 (when omicron was the predominant circulating strain) were allowed to return to work early if all symptoms had resolved excepting mild, intermittent cough and/or lingering loss of taste/smell, provided a rapid antigen test was negative upon return. Those with negative tests were allowed to return to work with the stipulations that they wear an N95 at all times and take breaks and eat meals apart from others. Those with positive tests on first attempt could return 24-48 hours later to test again for as many days as needed to achieve a negative result or until they completed 10 days of restriction from work.
Results
Between January 2, 2022 and January 12, 2022 there were 309 total RAT done on 260 separate HCW on day 5-10 of illness. Overall, 43% (134 of 309) of all RAT were positive between days 5-10. The greatest percent positive RAT was noted among HCW returning for their first test on day 6 (58%). The rate of positivity was greatest (58%) among HCW returning for their first test on day 6. HCW returning on day 8 and 9 were less likely to have a positive test (26%, 19/74). In RAT positive HCW returning for their first test on days 5 or 6 (and for which line intensity was recorded) 49% (25/51) were recorded as having the darkest intensity on their RAT. HCW who test positive on their first test most often remained positive on their second test, with 56% of second tests, aggregated across all days 6-10, remaining positive. Over all first tests performed on days 5-10, boosted HCW were nearly twice as likely to test RAT positive: 53% (75 out of 141) of boosted HCW tested positive.
Discussion
More than 40% of vaccinated HCW who felt well enough to work still had positive RAT tests when presenting for a first test between days 5 and 10. Boosted individuals were nearly 3x as likely to result positive on day 5, their first day eligible for return, and ∼2x as likely to result positive on first RAT overall. New guidance provides clearance to exit isolation after 5 days from symptom onset, without the need for a negative rapid antigen test to exit, as long as symptoms are beginning to resolve. Per CDC, the guidance was driven by prior studies, mostly collected before Omicron and before most people were vaccinated or infected, that reported on symptom onset beginning one or more days after peak virus loads. In such an instance, where isolation based on symptom onset often did not begin until peak virus load was already attained, then release from isolation at 5 days would be appropriate. However, reports showing much earlier onset of symptoms, coupled with our own results here demonstrate that the relationship between symptom onset and peak virus load has changed, and 5 days from symptom onset may no longer be an appropriate window to end isolation without a negative rapid antigen test to support safe exit.
Conclusion
These results indicate that a substantial proportion of individuals with COVID-19 are likely still contagious after day 5 of illness regardless of symptom status. Early liberation from isolation should be undertaken only with the understanding that inclusion of individuals on day 6-10 of illness in community or work settings may increase the risk of COVID-19 spread to others which, in turn, may undermine the intended benefits to staffing by resulting in more sick workers.
Article activity feed
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Iain E. Buchan
Review 2: "High Rates of Rapid Antigen Test Positive After 5 days of Isolation for COVID-19"
While results were clearly presented, reviewers point out that the manuscript’s conclusions are not backed up by these results, and the discussion should be better supported by literature.
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Manuel Krone
Review 1: "High Rates of Rapid Antigen Test Positive After 5 days of Isolation for COVID-19"
While results were clearly presented, reviewers point out that the manuscript’s conclusions are not backed up by these results, and the discussion should be better supported by literature.
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Strength of evidence
Reviewers: M Krone (University Hospital Wuerzburg) | 📒📒📒 ◻️◻️
I. E. Buchan (University of Liverpool) | 📘📘📘📘📘 -
SciScore for 10.1101/2022.02.01.22269931: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis 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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.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:…
SciScore for 10.1101/2022.02.01.22269931: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis 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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.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.
Results from scite Reference Check: We found no unreliable references.
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