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AIMS Medical Science

2025, Volume 12, Issue 1: 1-12. doi: 10.3934/medsci.2025001
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Research article

Viral load dynamics of SARS-CoV-2 in the moderately symptomatic COVID-19 patients in Dak Lak, Viet Nam, 2021

  • 1.
    Department of Communicable Disease Control, Tay Nguyen Institute of Hygiene and Epidemiology, Buon Ma Thuot, Dak Lak province, Vietnam
  • 2.
    Department of Microbiology and Immunology, Tay Nguyen Institute of Hygiene and Epidemiology of Tay Nguyen, Buon Ma Thuot, Dak Lak province, Vietnam
  • 3.
    Dak Lak Department of Health, Buon Ma Thuot, Dak Lak province, Vietnam
  • Received: 06 July 2024 Revised: 31 October 2024 Accepted: 12 November 2024 Published: 07 January 2025

  • COVID-19 vaccines reduce infection, disease severity, and death by SARS-CoV-2 by reducing viral load. This study aimed to evaluate the change of cycle threshold (Ct) value in COVID-19 patients and investigate factors related to the Ct value change on the 3rd (D3), 7th (D7), 10th (D10), and 14th (D14) day after hospital admission in Dak Lak in 2021. Nasopharyngeal swabs and serum samples were obtained from 251 COVID-19 patients. Samples were collected on D3, D7, D10, and D14 after hospital admission and tested for SARS-CoV-2 by real-time RT-PCR tests. Ct values were categorized as high viral load, moderate viral, and low viral load. Electrochemiluminescence immunoassay was used to estimate the anti-SARS-CoV-2 antibodies. The results demonstrated that vaccinated individuals against COVID-19 have a faster rate of hospital discharge than the unvaccinated group, most clearly on D10. The Ct change on D10 of vaccinated individuals was statistically significantly higher (1.35 times) than of unvaccinated individuals (P < 0.01). The mean Ct values of unvaccinated individuals on D3, D7, D10, and D14 were lower than that of vaccinated individuals. However, there was a statistically significant increase in Ct of vaccinated individuals compared to unvaccinated individuals only on D10 and D14 (P < 0.03). The percentage of Ct value ≥ 30 and negative of vaccinated persons on D7 (60.9%) was similar to that of unvaccinated persons on D10 (59.4%) (P > 0.05). Vaccinated individuals at hospital admission with Ct ≤ 20 on D1 had a statistically significant decline in viral load on D10 and D14, 1.55 and 1.30 times higher compared to unvaccinated individuals (P < 0.05). The percentage of Ct ≥ 30 was significantly higher in males than females, especially on D7 and D14 with PR = 1.26 and 1.11 (P < 0.05). In conclusion, individuals vaccinated against COVID-19 had reduced transmission by a significant decline in viral load and recovered faster than unvaccinated individuals.

    Citation: Chien Chinh Vien, Tuan Van Le, Van Tuyet Thi Nguyen, Thang Nghia Hoang, Phila Nay. Viral load dynamics of SARS-CoV-2 in the moderately symptomatic COVID-19 patients in Dak Lak, Viet Nam, 2021[J]. AIMS Medical Science, 2025, 12(1): 1-12. doi: 10.3934/medsci.2025001

    Related Papers:

  • COVID-19 vaccines reduce infection, disease severity, and death by SARS-CoV-2 by reducing viral load. This study aimed to evaluate the change of cycle threshold (Ct) value in COVID-19 patients and investigate factors related to the Ct value change on the 3rd (D3), 7th (D7), 10th (D10), and 14th (D14) day after hospital admission in Dak Lak in 2021. Nasopharyngeal swabs and serum samples were obtained from 251 COVID-19 patients. Samples were collected on D3, D7, D10, and D14 after hospital admission and tested for SARS-CoV-2 by real-time RT-PCR tests. Ct values were categorized as high viral load, moderate viral, and low viral load. Electrochemiluminescence immunoassay was used to estimate the anti-SARS-CoV-2 antibodies. The results demonstrated that vaccinated individuals against COVID-19 have a faster rate of hospital discharge than the unvaccinated group, most clearly on D10. The Ct change on D10 of vaccinated individuals was statistically significantly higher (1.35 times) than of unvaccinated individuals (P < 0.01). The mean Ct values of unvaccinated individuals on D3, D7, D10, and D14 were lower than that of vaccinated individuals. However, there was a statistically significant increase in Ct of vaccinated individuals compared to unvaccinated individuals only on D10 and D14 (P < 0.03). The percentage of Ct value ≥ 30 and negative of vaccinated persons on D7 (60.9%) was similar to that of unvaccinated persons on D10 (59.4%) (P > 0.05). Vaccinated individuals at hospital admission with Ct ≤ 20 on D1 had a statistically significant decline in viral load on D10 and D14, 1.55 and 1.30 times higher compared to unvaccinated individuals (P < 0.05). The percentage of Ct ≥ 30 was significantly higher in males than females, especially on D7 and D14 with PR = 1.26 and 1.11 (P < 0.05). In conclusion, individuals vaccinated against COVID-19 had reduced transmission by a significant decline in viral load and recovered faster than unvaccinated individuals.



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    Acknowledgments


    We would like to thank all participants for their contribution to the study.

    Ethics approval of research and informed consent


    This study was approved by the Ethical Committee of Tay Nguyen Institute of Hygiene and Epidemiology, Vietnam (Approval number: 07/CN-VTN, dated 15th November 2021). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. All participants had provided written informed consent and assent, as appropriate, prior to study enrollment.

    Conflict of interest


    The authors declare no conflict of interest.

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