Advertisement

COVID-19 Follow up Testing

      Highlights

      • Positive cases of SARS-CoV-2 were seen in the Mayo Clinic FL COVID Virtual Clinic.
      • 70% of patients met CDC guidelines for release from quarantine & still tested (+).
      • The average time from onset of symptoms to negative testing was 19 days.

      Keywords

      Dear Editor,
      There is some uncertainty regarding the incubation period of the SARS-CoV-2 virus. There is also some uncertainly on the proportion of infected individuals who are asymptomatic carriers, and the timeframe from when a patient is infectious until becoming non-infectious.
      • Lauer S.A.
      • Grantz K.H.
      • Bi Q.
      • et al.
      The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application.
      We provide care for COVID-19 patients in the outpatient setting through a virtual clinic. Our patients have tested positive via nasopharyngeal swabs and RNA detection with RT-PCR. They are followed throughout their illness with visits at intervals based on the severity of their symptoms using telemedicine technology.
      The CDC has two strategies to determine when a patient with COVID-19 can discontinue self-isolation. One is a “test-based” strategy, and the other is a “symptom-based” strategy. The symptom-based-strategy recommends that COVID-19 patients can discontinue self-isolation when they have been afebrile for 72 hours without anti-pyretic medications, have improvement in respiratory symptoms, and have at least 10 days elapse since symptoms started, recently increased from 7 days. The test-based strategy requires resolution of fever without the use of anti-pyretics, improvement of respiratory symptoms, and two consecutive negative COVID-19 nasopharyngeal swabs collected ≥24 hours apart.

      Discontinuation of Isolation for Persons with COVID-19 Not in Healthcare Settings. https://www.cdc.gov/coronavirus/2019-ncov/hcp/disposition-in-home-patients.html.

      We decided as part of our COVID-19 Virtual Clinic to use the test-based strategy for all of our patients to better ensure that they were not contributing to the spread of disease. Our organization manufactures the test, so we had ample testing supplies and laboratory capacity. As this disease is a reportable condition, these patients were also followed by the respective county health departments. The county health departments were using the test-based strategy only for healthcare workers, or those with essential public service jobs.
      As of April 17, 2020, we have enrolled 97 patients in our COVID Virtual Clinic. Of these, 72 have been tested after being afebrile for at least 72 hours, and had 7 days pass since symptoms started, along with symptom improvement. That is, 72 patients met criteria for the original release from self-isolation with the symptom-based-strategy, but were tested using the test-based strategy. Of these, twenty-two (30.1%) tested negative upon the first two tests, while the vast majority of patients (69.9%) tested positive at this interval. Of the 69.9% who failed, thirty-six (72%) were positive on the first test, while fourteen (28%) had a negative first test but were positive on the second test. In our patient population, the average time from the onset of symptoms to negative testing is 19 days.
      This data shows that the CDC symptom-based-strategy may cause early release from isolation for COVID-19 patients and result in additional community transmission. Given this, it may be beneficial to prolong the self-isolation time to greater than 14 days after symptom onset.
      Sincerely,
      Amelita Woodruff, MD
      Katherine Walsh PA-C, MPH
      Dacre Knight, MD, MS

      References

        • Lauer S.A.
        • Grantz K.H.
        • Bi Q.
        • et al.
        The Incubation Period of Coronavirus Disease 2019 (COVID-19) From Publicly Reported Confirmed Cases: Estimation and Application.
        Ann Intern Med. 2020; ([Epub ahead of print 10 March 2020]https://doi.org/)https://doi.org/10.7326/M20-0504
      1. Discontinuation of Isolation for Persons with COVID-19 Not in Healthcare Settings. https://www.cdc.gov/coronavirus/2019-ncov/hcp/disposition-in-home-patients.html.