Sars cov 2 rapid antigen test

SARS-CoV-2 infection was detected by real-time reverse-polymerase chain reaction (RT-qPCR) with reverse transcriptase by Applied Biosystems 7500 (Applied Biosystems, Foster City, CA, USA), exclusively, between March 23 and November 30, 2020, as previously described [16 (link)]. Subsequently, the SARS-CoV-2 Roche SARS-CoV-2 rapid antigen test (Roche, Basel, Switzerland) or Abbott BinaxNOWTM 88 COVID-19 Ag Card (Abbott Laboratories, Abbott Park, IL, USA) determination was used for antigen detection in the nasopharyngeal swab following the manufacturer’s recommendations, between December 1, 2020, and March 29, 2021. In all hospitalized patients, the diagnosis of COVID-19 was confirmed by RT-qPCR.
All data from hospitalized patients and outpatients residing in the CDMX were added to the Epidemiological Surveillance System for Respiratory Diseases (SISVER) database [17 ] for each medical unit and included demographic data, medical unit, results of the SARS CoV-2 diagnostic test, residence, age, sex, date of onset of symptoms, date of admission to hospital, comorbidities, and date of death, among others. Additionally, the CDMX Government’s Digital Agency for Public Innovation completed the data, incorporating detailed information on the cases, as well as other indicators such as the number of beds available for COVID-19 care, hospitalization rates, and overall availability of beds.

Commercially available rapid antigen detection kit of SARS-CoV-2 (Abbott Panbio COVID-19 Ag Rapid Test, Roche SARS-CoV-2 Rapid Antigen Test, SD. Biosensor Standard Q COVID-19 Ag, and Fujirebio Espline SARS-CoV-2) were used according to the manufacturers’ instructions. For evaluation of clinical samples, each of the specimens were diluted three times with each extraction buffer and then subjected. Test line interpretations were made by at least two independent observers within the stipulated time.

SARS-CoV-2 antigen tests were performed on nasopharyngeal swabs using one of the following lateral flow antigen tests: Panbio COVID-19 Ag Rapid Test Device (Abbott, USA). SARS-CoV-2 Rapid Antigen Test (Roche, Switzerland), Standard Q COVID-19 Antigen Test (SD Biosensor, Korea), or CareStart COVID-19 Antigen Test (Access Bio, USA). All antigen tests were performed point-of-care according to each manufacturer’s instructions at public or private hospitals and clinics throughout Qatar with prior authorization and training by the Ministry of Public Health (MOPH). Antigen test results were electronically reported to the MOPH in real time using the Antigen Test Management System which is integrated with the national COVID-19 database.

Two swabs per patient were taken by experienced medical staff. The first probe was analysed using the point-of-care device (SARS-CoV-2 Rapid Antigen Test (Roche Diagnostics). Outcome was recorded 15 minutes after sampling as positive, negative, or invalid. Only one case (1/542 = 0.2%), a 31 year old male patient with a sore throat two days prior testing and a negative rt-PCR, showed an invalid AG-rt reading, which was not included in analysis. All rt-PCR analyses using the second probe of each patient was conducted in hospital’s laboratories or in other special laboratories. Rt-PCR results were collected as quantitative (Ct) and qualitative (positive or negative) parameters. Ct was reported in 202 of 213 cases.

Patients admitted to a private practice with a special focus on infectious diseases
(Praxiszentrum Alte Mälzerei, Regensburg, Germany) were screened for inclusion in this
study. To be included, patients had to exhibit COVID-19–like symptoms for not longer than
72 h as well as a positive antigen point-of-care test (SARS-CoV-2 Rapid Antigen Test;
Roche) at the time of inclusion in the study. Exclusion criteria were indication for
intubation or mechanical ventilation and severe stomatitis. Written informed consent was
obtained from all individual participants included in the study. Besides demographic data
such as age and gender, also anamnestic data such as COVID-19 vaccination status, history
of infection with SARS-CoV-2, and time periods since the last vaccine shot or infection
were recorded.

Several studies have remarked that testing sensitivity in clinical practice can be much lower than the theoretical detection limit would indicate. For example, Kucirka et al. (40 (link)) suggested that the sensitivity of a RT-PCR test depends on the time since infection (a reflection of the VL) and that it is never more than 80%. Although there are many RT-PCR test platforms and protocols in use, the general sensitivity over the infection duration is likely not substantially different. To examine testing protocols under the best of circumstances, we assume much better performance for RT-PCR tests than suggested by Kucirka et al. (40 (link)), with no detection if the VL is below 10³ copies/mL but 90% sensitivity for any VL above that (SI Appendix, Fig. S6B). We compare this test with an antigen test with characteristics as presented in Kohmer et al. (29 (link)), who compared the performance of several antigen tests with the results of RT-PCR. Based on their data for the SARS-CoV-2 Rapid Antigen Test (Roche Diagnostics) versus the VL in the sample, we fit the performance of the test to a logistic type relation between VL and positivity detection yielding the curve shown in SI Appendix, Fig. S6C (see SI Appendix for further details). An infected person’s probability of being detected is a Bernoulli trial based on the sensitivity of the test (as in SI Appendix, Fig. S4).

SARS-CoV-2 antigen tests were performed on nasopharyngeal swabs using one of the following lateral flow antigen tests: Panbio COVID-19 Ag Rapid Test Device (Abbott, USA; sensitivity: 91.4%, specificity: 99.8%);⁴⁸ SARS-CoV-2 Rapid Antigen Test (Roche, Switzerland; sensitivity: 95.5%, specificity: 99.2%);⁴⁹ Standard Q COVID-19 Antigen Test (SD Biosensor, Korea; sensitivity: 90.7%, specificity: 98.9%);⁵⁰ or CareStart COVID-19 Antigen Test (Access Bio, USA; sensitivity: 93.8%, specificity: 99.3%)⁵¹ . All antigen tests were performed point-of-care according to each manufacturer’s instructions at public or private hospitals and clinics throughout Qatar with prior authorization and training by the Ministry of Public Health (MOPH). Antigen test results were electronically reported to the MOPH in real-time using the Antigen Test Management System, which is integrated with the national COVID-19 database.