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SARS-CoV-2 Surveillance in the National Football League
Quick Takes
- Routine RT-PCR testing protocols enabled early detection of infection, often when the person had low viral load and no symptoms.
- Cycle threshold (Ct) values produced by quantitative platforms can be useful in interpreting positive test results within a large, routinely tested population, with high Ct values potentially able to signal early infection.
- The Quidel Sofia antigen point-of-care test was unreliable and unable to detect infection in early stages, with negative results in 42% of adjudicated COVID-19 cases.
Study Questions:
What are the results of a rigorous, large-scale coronavirus disease 2019 (COVID-19) testing and monitoring program?
Methods:
The investigators describe the results of an intensive effort and the utility of daily testing across multiple platforms, including three nucleic acid amplification tests (NAATs) and a rapid antigen point-of-care (aPOC) test. The US National Football League (NFL) and the NFL Players Association (NFLPA) instituted a large-scale COVID-19 monitoring program involving daily testing using two reverse transcription polymerase chain reaction (RT-PCR) platforms (Roche cobas and Thermo Fisher QuantStudio), a transcription-mediated amplification platform (Hologic Panther), and an antigen point-of-care (aPOC) test (Quidel Sofia) for 32 NFL clubs in 24 states during the 2020 NFL season. NFL players and staff were the participants. SARS-CoV-2 test results were described in the context of medically adjudicated status. Cycle threshold (Ct) values are reported when available. Incidence rates were calculated as the number of new adjudicated cases out of the total number of persons tested in the period of interest. Distribution of Ct values for initial positive test results is presented for results obtained from the Roche cobas instrument.
Results:
A total of 632,370 tests administered across 11,668 persons identified 270 (2.4%) COVID-19 cases from August 1–November 14, 2020. Positive predictive values ranged from 73.0–82.0% across the RT-PCR platforms. High Ct values (33-37) often indicated early infection. For the first positive result, the median Ct value was 32.77 (interquartile range, 30.02-34.72) and 22% of Ct values were above 35. Among adjudicated COVID-19 cases tested with aPOC, 42.3% had a negative result. Positive concordance between aPOC test result and adjudicated case status increased as viral load increased.
Conclusions:
The authors concluded that routine RT-PCR testing allowed early detection of infection.
Perspective:
The intensive surveillance and mitigation work performed during the 2020 NFL season reports that frequent, routine RT-PCR testing protocols enabled early detection of infection, often when the person had low viral load and no symptoms. However, when the same sample was analyzed on two different platforms, there were instances of discordant results, indicating variability of test performance. Furthermore, Ct values produced by quantitative platforms can be useful in interpreting positive test results within a large, routinely tested population, with high Ct values potentially able to signal early infection. Of note, the Quidel Sofia aPOC test was unable to detect infection in its early stages in many instances, with negative results in 42% of adjudicated COVID-19 cases. These findings may help development of population-level SARS-CoV-2 testing and surveillance strategies to mitigate spread of infection during the pandemic.
Clinical Topics: COVID-19 Hub, Prevention, Sports and Exercise Cardiology
Keywords: Coronavirus, COVID-19, Football, False Negative Reactions, Occupational Health, Pandemics, Point-of-Care Systems, Predictive Value of Tests, Primary Prevention, Reverse Transcription, SARS-CoV-2, Seasons, Sports, Viral Load
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