Evaluation of two RT-PCR screening assays for identifying SARS-CoV-2 variants.

BACKGROUND: The recent emergence of new SARS CoV-2 variants (variants of concern, VOC) that spread rapidly and may lead to immune escape has emphasized the urgent need to monitor and control their spread. METHODS: We analyzed 2018 SARS-CoV-2 positive specimens collected between February 9 and March 22, 2021 using the Thermofisher® TaqPath™ COVID-19 CE-IVD RT-PCR kit (TaqPath) and the ID solutions® ID™ SARS-CoV-2/UK/SA Variant Triplex RT-PCR (ID triplex) assay to screen for VOCs. RESULTS: The ID triplex assay identified 62.8% of them as VOCs: 61.8% B.1.1.7 and 0.9% B.1.351/P.1. The agreement between the ID triplex results for B.1.1.7 and the TaqPath S gene target failure (SGTF)/ S gene target late detection (SGTL) profile for this variant agreed very well (k = 0.86). A low virus load was the main cause of discrepancies. Sequencing discordant results with both assays indicated that the TaqPath assay detected the B.1.1.7 lineage slightly better. Both assays suggested that the virus loads of B.1.1.7 variants were significantly higher than those of non-B.1.1.7 strains. Only 10/20 B1.351/P.1 strains detected with the ID triplex assay were confirmed by sequencing. CONCLUSIONS: We conclude that the SGTF/SGTL profiles identified using the TaqPath assay and ID triplex results are suitable for detecting the B.1.1.7 lineage. The ID triplex assay, which rapidly determines all three current VOCs simultaneously, could be a valuable tool for limiting virus spread by supporting contact-tracing and isolation.

Catastrophe risk models for evaluating disaster risk reduction investments in developing countries.

Major natural disasters in recent years have had high human and economic costs, and triggered record high postdisaster relief from governments and international donors. Given the current economic situation worldwide, selecting the most effective disaster risk reduction (DRR) measures is critical. This is especially the case for low- and middle-income countries, which have suffered disproportionally more economic and human losses from disasters. This article discusses a methodology that makes use of advanced probabilistic catastrophe models to estimate benefits of DRR measures. We apply such newly developed models to generate estimates for hurricane risk on residential structures on the island of St. Lucia, and earthquake risk on residential structures in Istanbul, Turkey, as two illustrative case studies. The costs and economic benefits for selected risk reduction measures are estimated taking account of hazard, exposure, and vulnerability. We conclude by emphasizing the advantages and challenges of catastrophe model-based cost-benefit analyses for DRR in developing countries.

A community-based approach to linking injection drug users with needed services through pharmacies: an evaluation of a pilot intervention in New York City.

Studies suggest that community-based approaches could help pharmacies expand their public health role, particularly pertaining to HIV prevention. Thirteen pharmacies participating in New York's Expanded Syringe Access Program, which permits nonprescription syringe sales to reduce syringe-sharing among injection drug users (IDUs), were enrolled in an intervention to link IDU syringe customers to medical/social services. Sociodemographics, injection practices, beliefs about and experiences with pharmacy use, and medical/social service utilization were compared among 29 IDUs purchasing syringes from intervention pharmacies and 66 IDUs purchasing syringes from control pharmacies using chi-square tests. Intervention IDUs reported more positive experiences in pharmacies than controls; both groups were receptive to a greater public health pharmacist role. These data provide evidence that community-based participatory research aided in the implementation of a pilot structural intervention to promote understanding of drug use and HIV prevention among pharmacy staff, and facilitated expansion of pharmacy services beyond syringe sales in marginalized drug-using communities.

Radiation detectors in nuclear medicine.

Single-photon-emitting or positron-emitting radionuclides employed in nuclear medicine are detected by using sophisticated imaging devices, whereas simpler detection devices are used to quantify activity for the following applications: measuring doses of radiopharmaceuticals, performing radiotracer bioassays, and monitoring and controlling radiation risk in the clinical environment. Detectors are categorized in terms of function, the physical state of the transducer, or the mode of operation. The performance of a detector is described by the parameters efficiency, energy resolution and discrimination, and dead time. A detector may be used to detect single events (pulse mode) or to measure the rate of energy deposition (current mode). Some detectors are operated as simple counting systems by using a single-channel pulse height analyzer to discriminate against background or other extraneous events. Other detectors are operated as spectrometers and use a multichannel analyzer to form an energy spectrum. The types of detectors encountered in nuclear medicine are gas-filled detectors, scintillation detectors, and semiconductor detectors. The ionization detector, Geiger-Müller detector, extremity and area monitor, dose calibrator, well counter, thyroid uptake probe, Anger scintillation camera, positron emission tomographic scanner, solid-state personnel dosimeter, and intraoperative probe are examples of detectors used in clinical nuclear medicine practice.

Parathyroid adenomas: accurate detection and localization with Tc-99m sestamibi SPECT.

PURPOSE: To evaluate the ability to detect and localize parathyroid adenomas with technetium-99m sestamibi single photon emission computed tomography (SPECT). MATERIALS AND METHODS: Forty-seven adult patients underwent Tc-99m sestamibi SPECT. Early (15-30 minutes after injection) and delayed (2-4 hours after injection) images were acquired. Thirty-three patients were examined for initial parathyroid surgery; the remaining 14, for repeat surgery because of persistent or recurrent hyperparathyroidism. SPECT reprojection images viewed in a rotating cine-display mode were read independently by two nuclear medicine physicians who were blinded to the results of other localization studies. Thirty-seven patients underwent subsequent neck exploration. SPECT findings were compared with surgical and histopathologic findings. RESULTS: In the 37 patients who underwent surgery, parathyroid adenomas were confirmed in 34 (92%) and hyperplasia in three (8%). In 31 patients, adenomas were correctly detected and localized with early SPECT images (sensitivity, 91%). In contrast, the sensitivity of delayed SPECT images was 74% (25 of 34 patients) for detection and 32% (11 of 34 patients) for localization. Early SPECT images were significantly better for localization (P < .001) and detection (P = .03). CONCLUSION: For Tc-99m sestamibi parathyroid imaging, early SPECT images were the most accurate in the detection and localization of parathyroid adenomas.

Validation of simultaneous PET emission and transmission scans.

A technique for performing simultaneous PET emission and transmission scans is validated in a fluoro-deoxyglucose study. A point source masked into a fan beam of annihilation photons orbits the patient section under study. Coincident events are sorted into two buffers, or rejected, based on the source's position. Both static and dynamic frames of independent and simultaneous studies are compared. The noise effective count rate is reduced to 62% of the value during normal studies. However, the increase in the coefficient of variation in cortical regions is less than 6%. The RMS difference between profile contours through many brain regions is approximately 40% higher comparing two simultaneous emission/transmission scans than when the same analysis is performed on independent emission scans. This difference appears to be due to the noise patterns arising from the use of different transmission scans.

The application of a masked orbiting transmission source for attenuation correction in PET.

A new technique for attenuation correction in positron emission tomography is introduced and evaluated. Transmission scans are performed with a point source of 68Ge encapsulated in a lead collimator that masks the source into a fan beam in the scanning plane. The source orbits the patient section at the edge of the slice defining collimator. Only events acquired by detector pairs that are collinear with the source are used to calculate the attenuation coefficients. Events from detector pairs that are nearly collinear are rejected, while those from detector pairs that are far from collinear may be used to acquire a simultaneous emission scan. The coincident event rate per unit source activity is over twice that of rod and ring sources. This technique is compared with calculated outline and ring source attenuation correction techniques in a pie phantom. The linear attenuation coefficient for water was measured as 0.096 cm-1, and 0.094 cm-1 when the water contained 12 kBq/cc 68Ga, compared with 0.085 cm-1 for a ring source. Cerebral glucose utilization rates in a normal volunteer reconstructed with transmission scans performed pre- and postinjection of fluorodeoxyglucose show no significant differences. However, values of cortical glucose utilization average 12% above those measured with the fitted outline method in the highest cuts because of the obliqueness of the skull to the planes examined.