Seroprevalence of anti-SARS coronavirus 2 antibodies in Thai adults during the first three epidemic waves

Abstract

This study sought to determine the anti-SARS-CoV-2 antibody status of 4111 Thai people from May 2020 to April 2021, a period which spanned the first two and part of the third epidemic wave of the COVID-19 in Thailand. Participants comprised 142 COVID-19 patients, 2113 individuals at risk due to their occupations [health personnel, airport officers, public transport drivers, and workers in entertainment venues (pubs, bars and massage parlors)], 1856 individuals at risk due to sharing workplaces or living communities with COVID-19 patients, and 553 Thai citizens returning after extended periods in countries with a high disease prevalence. All sera were tested in a microneutralization assay and a chemiluminescence immunoassay (CLIA) for IgG against the N protein. Furthermore, we performed an immunofluorescence assay to resolve discordant results between the two assays. Antibody responses developed in 88% (15 of 17) of COVID-19 patients at 8 days and in 94-100% between 15 and 60 days after disease onset. Neutralizing antibodies persisted for at least 8 months, longer than the IgG did, against the N protein. None of the health providers, airport officers, and public transport drivers were seropositive, while the antibodies were present in 0.44% of entertainment workers. This study showed the seropositivity of 1.9, 1.5, and 7.5% during the 3 epidemic waves, respectively, in Bangkok residents who were at risk due to sharing workplaces or communities with COVID-19 patients. Also, antibody prevalence was 1.3% in Chiang Mai people during the first epidemic wave, and varied between 6.5 and 47.0% in Thais returning from high-risk countries. This serosurveillance study found a low infection rate of SARS-CoV-2 in Thailand before the emergence of the Delta variant in late May 2021. The findings support the Ministry of Public Health’s data, which are based on numbers of patients and contact tracing.

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Jan 25, 2022

SciScore for 10.1101/2022.01.18.22269501: (What is this?)

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

Table 1: Rigor

Ethics	IRB: Ethical statement: Usage of human sera from participants of age older than 18 received approval from the Mahidol University Central Institutional Review Board (MU-CIRB) under protocol number MU-COVID2020.001/2503. Consent: In the enrollment process for participants in groups 2 and 3, epidemiologists explained the purpose of the study to obtain written consent for interviewing about their demographics, occupation, workplace, residence, and general health condition, including a donation of 5-8 ml of blood, with specimens labeled using ID codes. 4) Thai citizens in state quarantines, when arrived Thailand after extended duties in countries with known SARS-CoV-2 outbreaks.
Sex as a biological variable	not detected.
Randomization	not detected.
Blinding	not detected.
Power Analysis	not detected.
Cell Line Authentication	not detected.

Table 2: Resources

Antibodies
Sentences	Resources
Blood specimens were collected for anti-SARS-CoV-2 antibody testing [along with real-time reverse transcription-polymerase chain reaction (RT-PCR)] to support active case surveillance activities conducted by the Institute for Urban Disease Control and Prevention (IUDC), DDC, MoPH.	anti-SARS-CoV-2 suggested: None
When results of the two assays were concordant, the test serum was considered positive or negative for anti-SARS antibodies.	anti-SARS suggested: None
A titer of 10 or greater was considered positive for NT antibody.	NT suggested: None
Experimental Models: Cell Lines
Sentences	Resources
The assay employed SARS-CoV-2-infected Vero cells deposited on microscopic slides as the test antigens.	Vero suggested: CLS Cat# 605372/p622_VERO, RRID:CVCL_0059)
Software and Algorithms
Sentences	Resources
Chemiluminescence immunoassay: CLIA using Architect auto-analyzer (Abbott Laboratories, USA) is the two-step, fully automated immunoassay that qualitatively detected binding between the SARS-CoV-2 nucleoprotein (N) antigen coated on paramagnetic microparticles and human IgG in the test sera.	Abbott Laboratories suggested: None
Statistical analysis: R square (R2), mean, and standard deviation (SD) were determined, and figures were drawn using GraphPad Prism version 8.4.3 for Windows (GraphPad Software, La Jolla, California, USA).	GraphPad Prism suggested: (GraphPad Prism, RRID:SCR_002798) GraphPad suggested: (GraphPad Prism, RRID:SCR_002798)
The McNemar test was carried out and 95% confidence interval (95% CI) calculated by SPSS Statistic software version 18.0.	SPSS suggested: (SPSS, RRID:SCR_002865)

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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

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.

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