Retrospective Pooled Screening for SARS-CoV-2 RNA in late 2019

Reports have emerged documenting earlier SARS-CoV-2 cases than previously recognized. To investigate this possibility in the Bay Area, we retrospectively tested 1,700 samples from symptomatic individuals for the last 2 months of 2019. No SARS-CoV-2 positive pools were identified, consistent with limited transmission in this population at this time.

the last two months of 2019 to investigate possible early circulation of SARS-CoV-2 in this area. All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. . https://doi.org/10.1101/2020 We performed a retrospective study that evaluated all available nasopharyngeal swab samples institutional review board (IRB), and individual patient consent was waived.

2
A total of 1700 individual nasopharyngeal specimens, corresponding to 170 pools, were included 5 3 for SARS-CoV-2 testing. Of these, 841 samples were previously tested and negative by the  In this study, 1,700 nasopharyngeal samples collected from symptomatic individuals in the last 6 2 two months of 2019 were screened by pooled testing, and no case of COVID-19 was detected. All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. . https://doi.org/10.1101/2020.05.14.20102079 doi: medRxiv preprint 5 to retrospectively identify "patient zero" in different geographic areas to better understand the 6 6 spread of SARS-CoV-2, and to inform current and future surveillance strategies for emerging 6 7 infectious diseases. Indeed, given the high volume of international travel prior to implementation 6 8 of travel restrictions, travel-associated COVID-19 cases may have occurred in the U.S. earlier 6 9 than previously recognized (8). However, monitoring for early community transmission of 7 0 COVID-19 in the U.S was challenging due its similar clinical presentation to other respiratory This study is limited by its sampling from a single institution, corresponding to a population that 7 9 may not be representative of the underlying area as a whole. Further retrospective SARS-CoV-2 8 0 RT-PCR screening using specimens collected at other institutions throughout the U.S. will be 8 1 necessary to fully understand early community transmission in this country. This work will 8 2 complement phylogenetic viral sequence analysis and large-scale seroprevalence studies to 8 3 characterize the regional and national emergence of SARS-CoV-2. Furthermore, it is possible 8 4 that the use of pooled testing have led to lower sensitivity; however, pool sizes of 10 samples have been shown to maintain high performance compared to individual samples (12). All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. . https://doi.org/10.1101/2020.05.14.20102079 doi: medRxiv preprint 6 In summary, we employed a pooled screening strategy to investigate local community  All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
The copyright holder for this preprint this version posted May 18, 2020. All rights reserved. No reuse allowed without permission.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
(which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.