Alliance for Pandemic Preparedness

June 9, 2021

Ct Values Do Not Predict SARS-CoV-2 Transmissibility in College Students

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  • PCR cycle threshold (Ct) values, a proxy measurement for viral load, were not significantly different between SARS-CoV-2-infected individuals with at least one confirmed infected contact (i.e., spreaders) (n=94) and infected individuals with no infected contacts (i.e., non-spreaders) (n=101) in a retrospective study of routine screening data from Tulane University obtained between September and October 2020 (n=7,440 students). The authors suggest that viral load alone cannot predict transmission risk.  Mean Ct values were significantly lower among symptomatic spreaders than asymptomatic non-spreaders, suggesting that the presence of symptoms and high viral load could increase risk of transmission.  The authors suggest that sensitive methods to detect asymptomatic persons with sufficient levels of virus to transmit are needed.

Tian et al. (June 5, 2021). Ct Values Do Not Predict SARS-CoV-2 Transmissibility in College Students. The Journal of Molecular Diagnostics. https://doi.org/10.1016/j.jmoldx.2021.05.012