Original Research

COVID-19 positive cases among asymptomatic individuals during the second wave in Ndola, Zambia

Jonathan Gwasupika, Victor Daka, Justin Chileshe, Moses Mukosha, Steward Mudenda, Bright Mukanga, Ruth L. Mfune, Gershom Chongwe
African Journal of Laboratory Medicine | Vol 12, No 1 | a2119 | DOI: https://doi.org/10.4102/ajlm.v12i1.2119 | © 2023 Jonathan Gwasupika, Victor Daka, Justin Chileshe, Moses Mukosha, Steward Mudenda, Bright Mukanga, Ruth L. Mfune, Gershom Chongwe | This work is licensed under CC Attribution 4.0
Submitted: 11 November 2022 | Published: 31 May 2023

About the author(s)

Jonathan Gwasupika, Department of Clinical Sciences, Tropical Diseases Research Centre, Ndola, Zambia
Victor Daka, Department of Public Health, School of Medicine, Copperbelt University, Ndola, Zambia
Justin Chileshe, Department of Biomedical Sciences, Tropical Diseases Research Centre, Ndola, Zambia
Moses Mukosha, Department of Pharmacy, School of Health Sciences, University of Zambia, Lusaka, Zambia
Steward Mudenda, Department of Pharmacy, School of Health Sciences, University of Zambia, Lusaka, Zambia
Bright Mukanga, Department of Public Health, School of Medicine, Copperbelt University, Ndola, Zambia
Ruth L. Mfune, Department of Public Health, School of Medicine, Copperbelt University, Ndola, Zambia
Gershom Chongwe, Tropical Diseases Research Centre, Ndola, Zambia

Abstract

Background: Coronavirus disease 2019 (COVID-19) is a worldwide public health concern for healthcare workers. About 80% of cases appear to be asymptomatic, and about 3% may experience hospitalisation and later die. Less than 20% of studies have looked at the positivity rate of asymptomatic individuals.

Objective: This study investigated the COVID-19 positivity rates among asymptomatic individuals during the second COVID-19 wave at one of Zambia’s largest testing centre.

Methods: This was a retrospective cross-sectional study conducted on routine surveillance and laboratory data at the Tropical Diseases Research Centre COVID-19 laboratory in Ndola, Zambia, from 01 December 2020 to 31 March 2021. The study population was made up of persons that had tested for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection as a requirement for travel. Microsoft Excel was used to come up with an epidemiological curve of daily COVID-19 positive cases; proportions for gender were described using frequencies and percentages.

Results: A total of 11 144 asymptomatic individuals tested for SARS-CoV-2 were sampled for the study and 1781 (16.0%) returned positive results. The median age among those tested was 36 years (interquartile range: 29–46). Testing for COVID-19 peaked in the month of January 2021 (37.4%) and declined in March 2021 (21.0%). The epidemiological curve showed a combination of continuous and propagated point-source transmission.

Conclusion: The positivity rate of 16.0% among asymptomatic individuals was high and could imply continued community transmission, especially during January 2021 and February 2021. We recommend heightened testing for SARS-CoV-2 among asymptomatic individuals.

What this study adds: This study adds critical knowledge to the transmission of COVID-19 among asymptomatic travellers who are usually a key population in driving community infection. This knowledge is critical in instituting evidence-based interventions in the screening and management of travellers, and its control.


Keywords

asymptomatic individuals; COVID-19 disease; positivity rate; SARS-CoV-2; Zambia

Sustainable Development Goal

Goal 3: Good health and well-being

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