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. 2022 Jan 29;74(2):271-277.
doi: 10.1093/cid/ciab360.

Retrospective Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Symptomatic Patients Prior to Widespread Diagnostic Testing in Southern California

Evann E Hilt  1 , James Boocock  2   3   4 , Marisol Trejo  1 , Catherine Q Le  1 , Longhua Guo  2   3   4 , Yi Zhang  2 , Laila Sathe  1 , Valerie A Arboleda  1   2 , Yi Yin  2 , Joshua S Bloom  2   3 , Pin-Chieh Wang  5 , Joann G Elmore  5 , Leonid Kruglyak  2   3   4 , Lasata Shrestha  6 , Shah A Mohamed Bakhash  6 , Michelle Lin  6 , Hong Xie  6 , Meei-Li Huang  6 , Pavitra Roychoudhury  6 , Alexander Greninger  6 , Sukantha Chandrasekaran  1 , Shangxin Yang  1 , Omai B Garner  1
Affiliations

Retrospective Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in Symptomatic Patients Prior to Widespread Diagnostic Testing in Southern California

Evann E Hilt et al. Clin Infect Dis. .

Abstract

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused one of the worst pandemics in recent history. Few reports have revealed that SARS-CoV-2 was spreading in the United States as early as the end of January. In this study, we aimed to determine if SARS-CoV-2 had been circulating in the Los Angeles (LA) area at a time when access to diagnostic testing for coronavirus disease 2019 (COVID-19) was severely limited.

Methods: We used a pooling strategy to look for SARS-CoV-2 in remnant respiratory samples submitted for regular respiratory pathogen testing from symptomatic patients from November 2019 to early March 2020. We then performed sequencing on the positive samples.

Results: We detected SARS-CoV-2 in 7 specimens from 6 patients, dating back to mid-January. The earliest positive patient, with a sample collected on January 13, 2020 had no relevant travel history but did have a sibling with similar symptoms. Sequencing of these SARS-CoV-2 genomes revealed that the virus was introduced into the LA area from both domestic and international sources as early as January.

Conclusions: We present strong evidence of community spread of SARS-CoV-2 in the LA area well before widespread diagnostic testing was being performed in early 2020. These genomic data demonstrate that SARS-CoV-2 was being introduced into Los Angeles County from both international and domestic sources in January 2020.

Keywords: SARS-CoV-2; diagnostic testing.

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