Field evaluation of Rapid SARS-Cov2 Antigen screening test on self-collected deep throat saliva samples in Malaysia

  1. Noorliza Mohamad Noordin
  2. Steven Chee Loon Lim
  3. Zhuo-zhi Lim
  4. Teck-Onn Lim

Reviewed by

Read the full article See related articles

Listed in

Log in to save this article

Abstract

Low cost Rapid Antigen Tests are widely used in Malaysia and the government has also mandated worksite screening as a condition for reopening. Numerous RAT kits have been approved by the Malaysian Medical Device Authority. However, it remains uncertain how these kits would perform in the field.

We enrolled workers between June and September 2021 from 23 worksites. They were trained and experienced in performing RAT selftest by virtue of their worksite participation in routine screening program. These workers also had reverse transcriptase polymerase chain reaction tests in the course of mass screening or contact tracing. We also enrolled patients with PCR confirmed Covid19 from a quarantine centre. These patients were instructed on selftesting and then immediately perform RAT under supervision. Two manufacturers donated RAT for this study.

A total of 340 participants were enrolled, 130 were from quarantine centre and 210 from worksites. The overall sensitivity of RAT compared to PCR was 70 percent. The specificity was 91 percent. Sensitivity decreased with increasing PCR cycle threshold values. Sensitivity is also lower among untrained subjects at each level of Ct. Logistic regression analysis confirmed false negative result is associated with Ct and participants prior training and experience.

This study shows that in the real world, RAT performance were markedly lower than that reported by the manufacturers. The test sensitivity is dependent on the operator training and experience, as well as on viral load as measured by Ct. User training and repeated testing for screening purpose is necessary to mitigate the low sensitivity of RAT.

Article activity feed

  1. ScreenIT

    SciScore for 10.1101/2021.12.20.21268141: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsIRB: The Ministry of Health’s (MOH) Medical and Research Ethics Committee approved the study and all subjects gave written informed consent.
    Consent: The Ministry of Health’s (MOH) Medical and Research Ethics Committee approved the study and all subjects gave written informed consent.
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study has limitations. The sample size is small. While we have used a convenient sample, deliberately enriched with RT-PCR positive subjects, the subjects are likely to be representative of the population who routinely undergo screening in Malaysia. We have also not been able to collect data on symptoms, another factor known to affect test performance9,10,11. Some RT-PCR testing were performed a day or 2 prior to RAT, which may also influence the results.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  2. Version published to 10.1101/2021.12.20.21268141v1 on medRxiv