Early Identification of SARS-CoV-2 Emergence in the DoD via Retrospective Analysis of 2019-2020 Upper Respiratory Illness Samples

The first case of non-travel related SARS-COV-2 was detected late February in California, however initially stringent testing criteria and subsequent delay of diagnostic testing made it difficult to identify those who could have acquired it through community spread. Early speculation was that the virus may have been circulating from at least January [1], and environmental sampling suggests that versions of this virus were found months before the first human samples were identified [2]. Here we performed a retrospective study from residual samples collected from a global respiratory surveillance effort to establish a tentative timeline by which this virus was circulating in the US military population. We performed RT-PCR for SARS-COV-2 and compared the dates of these cases to the first cases identified in respective states and counties using the Johns Hopkins COVID tracker website. Twenty-four positive samples were identified out of approximately 7,000 tested. Although we found some early cases in certain regions, we did not see circulation before late February in samples collected both in the US and outside the USA.