Efficient Tracing of the SARS-CoV-2 Omicron Variants in Santa Barbara County Using a Rapid Quantitative Reverse Transcription PCR Assay.

The emergence of the SARS-CoV-2 Omicron variant in 2021 is associated with a global surge of cases in late 2021 and early 2022. Identifying the introduction of novel SARS-CoV-2 variants to a population is imperative to inform decisions by clinicians and public health officials. Here, we describe a quantitative reverse transcription PCR-based assay (RT-qPCR) targeting unique mutations in the Omicron BA.1/BA1.1 and BA.2 viral genomes. This assay accurately and precisely detect the presence of these Omicron variants in patient samples in less than four hours. Using this assay, we tested 270 clinical samples and detected the introduction of Omicron BA.1/BA1.1 and BA.2 in the Santa Barbara County (SBC) population in December 2021 and February 2022, respectively. Identifying Omicron variants using this RT-qPCR assay showed complete concordance with whole viral genome sequencing; both assays indicated that Omicron was the dominant variant in SB County. Our data substantiate that RT-qPCR-based virus detection assays offer a fast and inexpensive alternative to NGS for virus variant-specific detection approach, which allows streamlining the detection of Omicron variants in patient samples.

CREST, a Cas13-Based, Rugged, Equitable, Scalable Testing (CREST) for SARS-CoV-2 Detection in Patient Samples.

The COVID-19 pandemic has taken a devastating human toll worldwide. The development of impactful guidelines and measures for controlling the COVID-19 pandemic requires continuous and widespread testing of suspected cases and their contacts through accurate, accessible, and reliable methods for SARS-CoV-2 detection. Here we describe a CRISPR-Cas13-based method for the detection of SARS-CoV-2. The assay is called CREST (Cas13-based, rugged, equitable, scalable testing), and is specific, sensitive, and highly accessible. As such, CREST may provide a low-cost and dependable alternative for SARS-CoV-2 surveillance. © 2022 Wiley Periodicals LLC. Basic Protocol: Cas13-ased detection of SARS-CoV-2 genetic material using a real-time PCR detection system Alternate Protocol: Cas13-based detection of SARS-CoV-2 genetic material using a fluorescence viewer Support Protocol 1: LwaCas13a purification Support Protocol 2: In vitro transcription of synthetic targets.

Comparison of Severe Acute Respiratory Syndrome Coronavirus 2 Screening Using Reverse Transcriptase-Quantitative Polymerase Chain Reaction or CRISPR-Based Assays in Asymptomatic College Students.

Importance: The reopening of colleges and universities in the US during the coronavirus disease 2019 (COVID-19) pandemic is a significant public health challenge. The development of accessible and practical approaches for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in the college population is paramount for deploying recurrent surveillance testing as an essential strategy for virus detection, containment, and mitigation. Objective: To determine the prevalence of SARS-CoV-2 in asymptomatic participants in a university community by using CREST (Cas13-based, rugged, equitable, scalable testing), a CRISPR-based test developed for accessible and large-scale viral screening. Design, Setting, and Participants: For this cohort study, a total of 1808 asymptomatic participants were screened for SARS-CoV-2 using a CRISPR-based assay and a point-of-reference reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) test. Viral prevalence in self-collected oropharyngeal swab samples collected from May 28 to June 11, 2020, and from June 23 to July 2, 2020, was evaluated. Exposures: Testing for SARS-CoV-2. Main Outcomes and Measures: SARS-CoV-2 status, viral load, and demographic information of the study participants were collected. Results: Among the 1808 participants (mean [SD] age, 27.3 [11.0] years; 955 [52.8%] female), 732 underwent testing from May to early June (mean [SD] age, 28.4 [11.7] years; 392 [53.6%] female). All test results in this cohort were negative. In contrast, 1076 participants underwent testing from late June to early July (mean [SD] age, 26.6 [10.5] years; 563 [52.3%] female), with 9 positive results by RT-qPCR. Eight of these positive samples were detected by the CRISPR-based assay and confirmed by Clinical Laboratory Improvement Amendments-certified diagnostic testing. The mean (SD) age of the positive cases was 21.7 (3.3) years; all 8 individuals self-identified as students. These metrics showed that a CRISPR-based assay was effective at capturing positive SARS-CoV-2 cases in this student population. Notably, the viral loads detected in these asymptomatic cases resemble those seen in clinical samples, highlighting the potential of covert viral transmission. The shift in viral prevalence coincided with the relaxation of stay-at-home measures. Conclusions and Relevance: These findings reveal a shift in SARS-CoV-2 prevalence in a young and asymptomatic population and uncover the leading edge of a local outbreak that coincided with rising case counts in the surrounding county and the state of California. The concordance between CRISPR-based and RT-qPCR testing suggests that CRISPR-based assays are reliable and offer alternative options for surveillance testing and detection of SARS-CoV-2 outbreaks, as is required to resume operations in higher-education institutions in the US and abroad.