Seroprotection Against COVID-19 Among Urban Migrant Workers: Evidence to Inform Health Screening Policy
Keywords:
Migrant Workers , COVID-19 Seroprevalence , Anti-SARS-CoV-2 IgG , Health Screening Protocols , Urban HealthAbstract
While the COVID-19 pandemic is no longer classified as a public health emergency, it is crucial to maintain preventive measures to control its transmission, particularly among vulnerable population like migrant workers. The level of immunity against COVID-19 is a valuable tool for surveillance because it is still detectable for an extended period, while the current diagnostic methods such as Real-time PCR and Antigen test kits (ATK), are primarily sensitive to the initial infection phase. This study aimed to evaluate the immunity levels (IgG) against SARS-CoV-2 and analyze health policies related to renewal of work permits for these migrant workers. The research was a cross-sectional design, with the participants of 975 migrant workers in Bangkok, Pathum Thani, Samut Prakan, Nakhon Nayok, and Prachinburi. Data was collected from September 16, 2022, to December 31, 2022. The laboratory method to test COVID-19 immunity levels utilizes Electrochemiluminescence immunoassay (ECLIA). The study finding indicated that out of the migrant workers, 878 participants (90.1%) show positive immunity test results, while 97 participants (9.9%) showed negative results. Among those who positive immunity, the proportions from Vietnam, Laos, Myanmar, and Cambodia were 100% (4/4), 94.3% (50/53), 89.8% (733/816), and 89.1% (90/101) respectively. Notably, 64.3% (265 participants) showed immunity levels of 200 BAU/ml and above and reported a vaccination history of over 4 months. Additionally, 105 participants showed immunity levels ranging between 18-199 BAU/ml, having either a history of vaccination or prior infection. Conversely, there were 30 participants who tested negative for immunity, having no history of COVID-19 illness. Participants with immunity levels of 200 BAU/ml and above, along with a vaccination history of more than 4 months, were significantly associated with protection against COVID-19 infection (p-value <0.001). Thus, it is recommended that migrant workers who have been vaccinated for more than 4 months or lack immunity should consider receiving the COVID-19 vaccine to ensure comprehensive protection against the disease.
References
World Health Organization. Coronavirus disease (COVID-19): epidemiology update [Internet]. [cited 2026 Apr 3]. Available from: https://www.who.int
World Health Organization. Interim statement on COVID-19 vaccination [Internet]. [cited 2026 Apr 3]. Available from: https://www.who.int
Levin EG, Lustig Y, Cohen C, Fluss R, Indenbaum V, Amit S, et al. Waning immune humoral response to BNT162b2 COVID-19 vaccine over 6 months. N Engl J Med. 2021;385(24):e84.
Goldberg Y, Mandel M, Bar-On YM, Bodenheimer O, Freedman L, Haas EJ, et al. Waning immunity after the BNT162b2 vaccine in Israel. Lancet. 2021;398(10316):1,964–72.
Khoury DS, Cromer D, Reynaldi A, Schlub TE, Wheatley AK, Juno JA, et al. Neutralizing antibody levels are predictive of immune protection from symptomatic SARS-CoV-2 infection. Nat Med. 2021;27(7):1,205–11.
Lumley SF, O’Donnell D, Stoesser NE, Matthews PC, Howarth A, Hatch SB, et al. Antibody status and incidence of SARS-CoV-2 infection. N Engl J Med. 2021;384(6):533–40.
Bobrovitz N, Arora RK, Cao C, Boucher E, Liu M, Donnici C, et al. Global seroprevalence of SARS-CoV-2 antibodies: a systematic review. PLoS One. 2021;16(6):e0252617.
Rostami A, Sepidarkish M, Leeflang MMG, Riahi SM, Nourollahpour Shiadeh M, Esfandyari S, et al. SARS-CoV-2 seroprevalence worldwide: a systematic review. Clin Microbiol Infect. 2021;27(3):331–40.
Gudbjartsson DF, Norddahl GL, Melsted P, Gunnarsdottir K, Holm H, Eythorsson E, et al. Humoral immune response to SARS-CoV-2 in Iceland. N Engl J Med. 2020;383(18):1,724–34.
Sughayer MA, Mansour A, Al Nuirat A, Souan L, Ghanem M, Siag M. Seroprevalence of SARS-CoV-2 antibodies among healthcare workers. Int J Infect Dis. 2021;102:103–8.
European Centre for Disease Prevention and Control. COVID-19 surveillance report [Internet]. [cited 2026 Apr 3]. Available from: https://www.ecdc.europa.eu
Department of Disease Control, Ministry of Public Health Thailand. COVID-19 situation report [Internet]. [cited 2026 Apr 3]. Available from: https://ddc.moph.go.th
International Labour Organization. Protecting migrant workers during the COVID-19 pandemic [Internet]. [cited 2026 Apr 3]. Available from: https://www.ilo.org
World Health Organization. Health of migrants: report by the Secretariat [Internet]. [cited 2026 Apr 3]. Available from: https://www.who.int
Abbas KM, Kang GJ, Chen D, Werre SR, Marathe A. Demographics and COVID-19 vaccination strategy. EClinicalMedicine. 2021;31:100689.
Patel MK, Bergeri I, Bresee JS, Cowling BJ, Crowcroft NS, Fahmy K, et al. Evaluation of COVID-19 vaccine effectiveness. Vaccine. 2021;39(38):5,337–49.
Thompson MG, Stenehjem E, Grannis S, Ball SW, Naleway AL, Ong TC, et al. Effectiveness of COVID-19 vaccines. N Engl J Med. 2021;385(15):1,355–71.
Chen Y, Tong X, Li Y, Gu B, Yan J, Liu Y, et al. Longitudinal antibody responses to SARS-CoV-2. J Infect Dis. 2020;222(10):1,621–9.
Ebrahim SH, Ahmed QA, Gozzer E, Schlagenhauf P, Memish ZA. COVID-19 mitigation strategies. Lancet Infect Dis. 2020;20(6):e75–83.
Kluge HHP, Jakab Z, Bartovic J, D’Anna V, Severoni S. Refugee and migrant health in COVID-19 response. Lancet. 2020;395(10232):1,237–9.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2026 Journal of Disease and Health Risk DPC.3
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Copyright notice
Article published in the Journal of Disease and Health Risk DPC.3 Nakhon Sawan. It is considered a work of academic research and analysis as well as the personal opinion of the author. It is not the opinion of the Office of Disease Prevention and Control 3, Nakhon Sawan. Or the editorial team in any way Authors are responsible for their articles.
Privacy Policy
Name, address and e-mail address specified in the Journal of Disease and Health Risk DPC.3 Nakhon Sawan. It is used for identification purposes of the journal. And will not be used for any other purpose. Or to another person.
