Background Highly sensitive real-time reverse transcription polymerase chain reaction (RT-qPCR) methods have been developed for the detection of SARS-CoV-2. However, they are costly. Loop-mediated isothermal amplification (LAMP) assay has emerged as a novel alternative isothermal amplification method for the detection of nucleic acid. Methods A rapid, sensitive and specific real-time reverse transcription LAMP (RT-LAMP) assay was developed for SARS-CoV-2 detection. Results This assay detected one copy/reaction of SARS-CoV-2 RNA in 30 min. Both the clinical sensitivity and specificity of this assay were 100%. The RT-LAMP showed comparable performance with RT-qPCR. Combining simplicity and cost-effectiveness, this assay is therefore recommended for use in resource resource-limited settings.

Rapid diagnosis is an important intervention in managing the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) outbreak. Real time reverse transcription polymerase chain reaction (RT-qPCR) remains the primary means for diagnosing the new virus strain but it is time consuming and costly. Recombinase polymerase amplification (RPA) is an isothermal amplification assay that does not require a PCR machine. It is an affordable, rapid, and simple assay. In this study, we developed and optimized a sensitive reverse transcription (RT)-RPA assay for the rapid detection of SARS-CoV-2 using SYBR Green I and/or lateral flow (LF) strip. The analytical sensitivity and specificity of the RT-RPA assay were tested by using 10-fold serial diluted synthetic RNA and genomic RNA of similar viruses, respectively. Clinical sensitivity and specificity of the RT-RPA assay were carried out using 78 positive and 35 negative nasopharyngeal samples. The detection limit of both RPA and RT-qPCR assays was 7.659 and 5 copies/μL RNA, respectively with no cross reactivity with other viruses. The clinical sensitivity and specificity of RT-RPA were 98% and 100%, respectively. Our study showed that RT-RPA represents a viable alternative to RT-qPCR for the detection of SARS-CoV-2, especially in areas with limited infrastructure.

Background: Asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections are well documented. Healthcare workers (HCW) are at increased risk of infection due to occupational exposure to infected patients. We aim to determine the prevalence of SARS-CoV-2 antibodies among HCW who did not come to medical attention. Methods:We prospectively recruited 400 HCW from the National Public Health Laboratory and two COVID-19 designated public hospitals in Klang Valley, Malaysia between 13/4/2020 and 12/5/2020. Quota sampling was used to ensure representativeness of HCW involved in direct and indirect patient care. All participants answered a self-administered questionnaire and blood samples were taken to test for SARS-CoV-2 antibodies by surrogate virus neutralization test. Findings:The study population comprised 154 (38.5%) nurses, 103 (25.8%) medical doctors, 47 (11.8%) laboratory technologists and others (23.9%). A majority (68.9%) reported exposure to SARS-CoV-2 in the past month within their respective workplaces. Adherence to personal protection equipment (PPE) guidelines and hand hygiene were good, ranging from 91-100% compliance. None (95% CI: 0, 0.0095) of the participants had SARS-CoV-2 antibodies detected, despite 182 (45.5%) reporting some symptoms one month prior to study recruitment. One hundred and fifteen (29%) of participants claimed to have had contact with known COVID-19 persons outside of their workplace.Interpretation: Zero seroprevalence among HCW suggests a low incidence of undiagnosed COVID-19 infection in our healthcare setting during the first local wave of SARS-CoV-2 infection. The occupational risk of SARS-CoV-2 transmission within healthcare facilities can be prevented by adherence to infection control measures and appropriate use of PPE.

IntroductionHealthcare workers (HCW) are presumed to be at increased risk of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection due to occupational exposure to infected patients. We aim to determine the prevalence of anti-SARS-CoV-2 antibodies among asymptomatic HCW.MethodsWe prospectively recruited HCW from the National Public Health Laboratory and two COVID-19 designated public hospitals in Klang Valley, Malaysia between April 13th and May 12th, 2020. Quota sampling was applied to ensure adequate representation of the HCW involved in provision of care for patients directly and indirectly. All participants had worked in the respective healthcare facility for at least 30 days prior study enrollment. HCW who were previously confirmed with COVID-19 infection or listed as “patient under investigation” were excluded. A self-administered questionnaire was used to capture sociodemographic information, history of contact with COVID-19 cases within the past month, clinical signs and symptoms and adherence to universal precautions. Blood samples were taken to test for anti-SARS-CoV-2 antibodies by surrogate virus neutralization test.ResultsA total of 400 HCW were recruited, comprising 154 (38.5%) nurses, 103 (25.8%) medical doctors, 47 (11.8%) laboratory technologists and others (23.9%). The mean age was 35±7.8 years, with females predominant (74%). A majority (68.9%) reported direct contact with COVID-19 patients, body fluids of COVID-19 patients and/or contaminated objects and surfaces in the past month within their respective workplaces. Nearly all claimed to adhere to personal protection equipment (PPE) guidelines (97%-100% adherence) and hand hygiene practice (91%-96% adherence). None (95% CI: 0, 0.0095) of the participants had anti-SARS-CoV-2 antibodies detected, despite 135 (33.8%) reporting respiratory symptoms one month prior to study recruitment. One hundred and fifteen (29%) participants claimed to have contact with known COVID-19 persons outside of the workplace.ConclusionOur finding of zero seroprevalence among asymptomatic HCW suggests a low risk of asymptomatic COVID-19 infection in our healthcare setting; which is at expected levels for a country with an incidence of 26 per 100,000. The adequacy of PPE equipment and strict adherence to infection prevention and control measures offers considerable protection during contact with COVID-19 cases and should be ensured to prevent future nosocomial transmission.