Serological and PCR Testing for COVID-19

This is a screening study to measure symptomatic and asymptomatic carriage of SARS-CoV-2 in trial participants to help facilitate early detection of a second wave of SARS-CoV-2 infections. Specifically, this study aims to determine ; to assess the duration of immunity by assessing the number and speed at which trial participants were infected and cleared the virus with or without symptoms; and to determine the length of symptom onset in those with an active infection; levels of IgG antibodies by demographics (sex, age, ethnicity, and intensity of symptoms). Longitudinal assessment of antibody levels will additionally allow for assessment of the efficacy of any vaccines adminstered. This study also seeks to explore how many people are asymptomatic carriers. In addition, this study aims to help facilitate the development a quantitative laboratory reference test for antibodies (IgG).

By using multiple different tests, it can be determined if a person is currently infected with SARS-CoV-2 or whether they previously have been infected. This allows for the scanning of people with asymptomatic carriage of the virus, which is important to help reduce the spread of SARS-CoV-2 through contact with people unaware of infection.

Polymerase Chain Reaction (PCR) testing is routinely used to check for active SARS-CoV-2 infections. It measures whether viral RNA is present in an individual's system. All in-house PCR tests are verified by an independent laboratory to check for false positives.

Using a membrane-based immunoassay to detect IgG and IgM antibodies to SARS-CoV-2 in whole blood, serum or plasma specimens helps to assess whether an individual has previously had the virus and is potentially immune. IgG and IgM detection components are separate allowing for differential detection of each antibody.

To this date, 20904 PCR tests and 6848 antibody tests have been carried out in 2328 individuals, providing some interim data. Of the 20904 PCR tests, 17635 (84%) were negative and 132 (1%) were negative. Of the 6848 antibody tests, 706 (10%) were positive for IgG only, 64 (1%) were positive for IgM only, and 351 (5%) were positive for both IgG and IgM. 5710 (83%) tests were negative.

Of those individuals with a positive PCR test, 53% reported fever during the previous two months and 75% reported a loss of taste during the previous two months.

Interim results are shown in the medRxiv papers below:

https://www.medrxiv.org/content/10.1101/2020.12.08.20245894v2

https://www.medrxiv.org/content/10.1101/2021.04.09.21255200v1

• Determination of the duration of immunity to SARS-CoV-2 [Срок оценки: Through study completion, estimated 12 weeks]
• Development of a quantitative laboratory reference test for the measurement of SARS-CoV-2 [Срок оценки: Through study completion, estimated 12 weeks]
• Exploration of SARS-CoV-2 epidemiology [Срок оценки: Through study completion, estimated 12 weeks]