Post-vaccination SARS-COV-2 infections among vaccinated individuals tested at the unam molecular diagnostic laboratory, June 2021-May 2022
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Date
2024
Authors
Journal Title
Journal ISSN
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Publisher
University of Namibia
Abstract
Background: Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2). To curb the disease, COVID-19
vaccines were rolled out. However, because vaccines are not 100% protective against the virus,
post-vaccination SARS-CoV-2 infections (PVSI) do occur. Thus, the study aimed to analyze
the occurrence of post-vaccination SARS-CoV-2 infections among vaccinated individuals
tested at the UNAM Molecular Diagnostic Laboratory (UNAM-MDL) from June 2021 to May
2022.
Methods: We conducted a retrospective cohort study of SARS-CoV-2 immunized individuals
tested at the laboratory between June 2021 and May 2022. COVID-19 Case Investigation
Forms (CIFs) were reviewed, and data from 5389 individuals were collected based on inclusion
and exclusion criteria. Using Statistical Package for the Social Sciences (SPSS) v.26,
descriptive and inferential analysis was performed; this included logistic regression, Kaplan Meier survival curve, 95% confidence interval, and p-value < 0.05 statistical significance. The
study was conducted in compliance with ethical principles.
Results: The post-vaccination SARS-CoV-2 infection rate among vaccinated individuals was
99.8 per 1,000 population with a median age of 40 years and a mortality rate of 1.1 per 1,000.
The majority of individuals in the study were males, with 4016 (74.5%). Most individuals were
vaccinated with Sinopharm 2399 (44.5%), asymptomatic and had no comorbidities. Only 10
(2%) had sequenced data of the SARS-CoV-2 variants with three variants: Beta, Delta and
Omicron. PVSI were characterized as early post-vaccination 52 (9.7%), partially vaccinated
201(39%) and fully vaccinated 276 (51.3%). The survival distribution in the study was
statistically significant (p < 0.05). Age, number of doses and sex were shown to be significant
factors associated with PVSI.
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Conclusion: The study showed that PVSI occurred mostly among fully vaccinated individuals,
although without complications. Although the study's goal was to further knowledge of SARS CoV-2 infections following immunization, the significance of maintaining high vaccination
rates in Namibia is highlighted by our results. To protect against severe COVID-19, it is critical
to raise community health awareness and actively encourage public vaccination uptake
Description
A thesis submitted in fulfilment of the requirements for the degree of masters of science in applied field epidemiology/ laboratory management
Keywords
COVID-19, Vaccination, Variants, Post-vaccination infections, Namibia