Originally published by 2 Minute Medicine^® (view original article). Reused on AccessMedicine with permission.

1. No transmission events of SARS-CoV-2 during the 2019-2020 NBA season were observed despite 36 asymptomatic individuals with persistent positive RT-PCR tests engaging in close-proximity unmasked activities.

2. Persistent positive individuals continued to have detectable SARS-CoV-2 RNA for a mean of 31 days from initial infection despite having no symptoms.

Evidence Rating Level: 2 (Good)

Study Rundown:

The National Basketball Association (NBA) suspended its regular season on March 11, 2020 due to the SARS-CoV-2 pandemic. The suspension of the NBA persisted until July 2020, when the NBA had established protocols to continue operations in an enclosed campus in Orlando, Florida. The protocol included mandatory quarantine upon arrival, and daily SARS-CoV-2 testing for individuals who appear on campus. Safety precautions included serological testing for antiviral antibodies and reverse-transcriptase PCR to detect viral SARS-CoV-2 RNA. This retrospective cohort study was done to investigate if individuals who have symptomatically recovered from COVID-19 were still infectious, and to determine their SARS-CoV-2 test status. The studied included 3648 individuals and assessed for SARS-CoV-2 daily for the testing status of previously COVID-19 positive individuals, and for the detection of additional positive cases. Before campus arrival, 36 individuals received a SARS-CoV-2 infection diagnosis. However, upon arrival to the campus in Orlando, Florida no additional spread of SARS-CoV-2 had occurred, despite these 36 individuals having daily unmasked contact with others. The study also showed that upon having a positive SARS-CoV-2 test result, these 36 individuals would follow with negative test results in the subsequent days, with 12 out of the 36 individuals having negative RT-PCR results before testing positive again. These findings suggest that the 36 individuals who were once positive for SARS-CoV-2 and were asymptomatic were not infectious, and supports the CDC criteria for discontinuation of isolation in individuals who are asymptomatic after appropriate time-based isolation regardless of RT-PCR results. The main strength of this study was the study of a unique circumstance of a large sample size of unmasked individuals in close proximity for an extended period of time. It was also however limited in its applicability, as a large percentage of the population was male (79.9%), and the duration of testing varied amongst participants, as participants left the NBA campus asynchronously due to teams being eliminated from the NBA post-season. These results might also may not be applicable to emerging variants.

Click to read the study in JAMA Internal Medicine

Click to read an editorial in JAMA Internal Medicine

Relevant Reading:Assessment of SARS-CoV-2 RNA Test Results Among Patients Who Recovered From COVID-19 With Prior Negative Results

In-Depth [retrospective cohort]:

This retrospctive cohort study used data from the NBA Orlando, Florida campus during the 2019-2020 season and post-season from June 11, 2020 to October 19, 2020. NBA players, staff and vendors participated in this study for a total population of 3648 individuals. Participants were predominately young males(79.9% of participants were male, and 26.2% were under 30). From data collected before entry into the NBA campus 36 of the 3648 individuals were SARS-CoV-2 positive. This was confirmed from physician diagnosis and a positive RT-PCR, or an inconclusive RT-PCR but detectable SARS-CoV-2 antibodies. The patients were also asymptomatic. During the course of the NBA season and post-season, no additional individuals were diagnosed with COVID-19, despite unmasked activities. The estimated number of reported unmasked contacts with positive SARS-CoV-2 individuals was estimated to be at least 51 days per participant. Participant length of enrollment varied in the study, as individuals left the campus asynchronously due to elimination from the NBA Finals tournament. Daily testing of these 36 individuals also found that individuals who tested positive for SARS-CoV-2 did not test positive consistently, as individuals had a mean of 44 negative RT-PCR test results. 30 of the 36 individuals had at least one positive or inconclusive RT-PCR after initial infection and 12 of those 30 had negative test results in between positive results.

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