Real-world Evaluation of a Sample Pooling Strategy for Large-Scale Rapid COVID-19 Testing

Multiplex CLIA-waived point-of-care tests for SARS-CoV-2, influenza A and B, ± other respiratory pathogens: A systematic review

BACKGROUND

Many multiplex CLIA-waived point of care tests are available in the United States for community pharmacists to incorporate into their practice.

OBJECTIVE

To characterize the eleven multiplex CLIA-waived point of care tests available for detecting SARS-CoV-2 and influenza A and B ± other respiratory pathogens and summarize their performance characteristics from published studies.

METHODS

Food and Drug Administration websites and databases were utilized to identify currently available tests. Literature searches were conducted and most recently updated through July 21, 2023 to identify studies examining the tests' performance. Primary literature was included if it reported positive and negative percent agreement (PPA and NPA, respectively) for SARS-CoV-2 or influenza A or B, had a comparator, and was conducted in a CLIA-waived environment. Relevant study characteristics, including number of samples, sample collection method, age of participants, comparator, PPA/NPA for SARS-CoV-2, influenza A and B, and respiratory syncytial virus (RSV) were extracted. Data extraction was performed by two authors with any discordant data reconciled by a third author.

RESULTS

Twenty-eight studies met inclusion criteria. The PPA for SARS-CoV-2 ranged from 86.7% to 100%, and NPA ranged from 90.4% to 100%. The PPA for influenza A and B ranged from 92.9% to 100% and 95.3% to 100%, respectively, while NPA ranged from 96.6% to 100% and 98.2% to 100%, respectively. Both the Xpert Xpress Plus and SpotFire tests showed similar results for RSV with PPA ranging from 96.3% to 100% and NPA ranging from 98.4% to 100%.

CONCLUSION

Currently available multiplex POCT for SARS CoV-2 and influenza A and B ± RSV have demonstrated efficacy in detecting multiple pathogens in a single test. Pathogen detection, costs, materials needed to perform the test (eg, readers), and study data (PPA and NPA) should be utilized to help determine which tests should be ordered for a particular practice setting.

Genotypic diversity and long-term impact of human bocavirus on diarrheal disease: Insights from historical fecal samples in Brazil

This study aimed to investigate the frequency and genotypic diversity of human bocavirus (HBoV) in historical fecal samples collected before 2005 in Brazil and understand its natural history in patients with diarrhea. Between 1998 and 2005, 3347 samples were tested for HBoV by RT-PCR, with a detection rate of 5.8% (195/3347). Coinfection with norovirus (NoV) and human adenovirus (HAdV) was found in 34.9% (68/195), indicating HBoV's potential role as a causative agent of diarrheal disease. The detection rate varied over the years (p < 0.05), suggesting natural oscillatory fluctuations. HBoV was more prevalent in fall and winter, with higher positivity in children ≤5 years (p < 0.05), reinforcing that HBoV is an important pathogen in childhood diarrhea. Genotyping (32.8%; 64/195) revealed the circulation of HBoV-1 (79.7%, 51/64), HBoV-3 (12.5%, 8/64), HBoV-2 (6.2%, 4/64), and the rare HBoV-4 (1.6%, 1/64). Difference in HBoV-1 and HBoV-2/-3 mono-infections prevalence (p < 0.05), suggests a potential role of HBoV-1 in the pathogenicity of diarrheal disease. The study highlights HBoV's lasting impact on viral gastroenteritis in Brazil and emphasizes its genotypic diversity. Recommending screening for HBoV in public health laboratories is crucial for understanding its role in gastrointestinal diseases. The data also contribute to understanding the molecular characterization of enteric viruses in historical fecal samples.

Assuring safety of fecal microbiota transplantation in the COVID-19 era: A single-center experience

Background and Aim

Fecal microbiota transplantation (FMT) is used to treat recurrent or refractory Clostridioides difficile infection (CDI). In the past, screening of fecal donors required surveillance of personal behavior, medical history, and diseases that could be transmitted by the blood or fecal-oral route. In addition, the exclusion of multidrug-resistant organisms (MDROs) has been recommended since 2018. This task has become more complicated in the era of the coronavirus disease-2019 (COVID-19) pandemic. To prevent fecal transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is crucial to commence screening for SARS-CoV-2, alongside other traditional tests. Our aim was to investigate whether hidden carriers of SARS-CoV-2 were enrolled for stool donation, and the status of the presence or incidence of MDRO during fecal donation in Taiwan.

Methods

Fecal products collected from March 2019 to December 2022 were tested for MDRO and nucleic acid amplification tests for SARS-CoV-2 using the pooling method. The period of fecal product collection crossed the time before and during the COVID pandemic in Taiwan.

Results

A total of 151 fecal samples were collected. The fecal products were tested using polymerase chain reaction (PCR) to detect SARS-CoV-2. The results were negative for all stocks. This was similar to the results of MDRO testing. The safety of FMT products has been guaranteed during the pandemic.

Conclusion

Our FMT center produced MDRO-free and COVID-19-free products before and during the COVID-19 outbreak in Taiwan. Our protocol was effective for ensuring the safety of FMT products.

Effect of swab pooling on the Accula point-of-care RT-PCR for SARS-CoV-2 detection

Introduction

Swab pooling may allow for more efficient use of point-of-care assays for SARS-CoV-2 detection in settings where widespread testing is warranted, but the effects of pooling on assay performance are not well described.

Methods

We tested the Thermo-Fisher Accula rapid point-of-care RT-PCR platform with contrived pooled nasal swab specimens.

Results

We observed a higher limit of detection of 3,750 copies/swab in pooled specimens compared to 2,250 copies/swab in individual specimens. Assay performance appeared worse in a specimen with visible nasal mucous and debris, although performance was improved when using a standard laboratory mechanical pipette compared to the transfer pipette included in the assay kit.

Conclusion

Clinicians and public health officials overseeing mass testing efforts must understand limitations and benefits of swab or sample pooling, including reduced assay performance from pooled specimens. We conclude that the Accula RT-PCR platform remains an attractive candidate assay for pooling strategies owing to the superior analytical sensitivity compared to most home use and point-of-care tests despite the inhibitory effects of pooled specimens we characterized.

An improvement of current hypercube pooling PCR tests for SARS-CoV-2 detection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic can be effectively controlled by rapid and accurate identification of SARS-CoV-2-infected cases through large-scale screening. Hypercube pooling polymerase chain reaction (PCR) is frequently used as a pooling technique because of its high speed and efficiency. We attempted to implement the hypercube pooling strategy and found it had a large quantization effect. This raised two questions: is hypercube pooling with edge = 3 actually the optimal strategy? If not, what is the best edge and dimension? We used a C++ program to calculate the expected number of PCR tests per patient for different values of prevalence, edge, and dimension. The results showed that every edge had a best performance range. Then, using C++ again, we created a program to calculate the optimal edge and dimension required for pooling samples when entering prevalence into our program. Our program will be provided as freeware in the hope that it can help governments fight the SARS-CoV-2 pandemic.