Faculty of Health Sciences (ETDs)

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Subject: search.filters.subject.Influenza vaccination

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    Defining Fc-mediated Functions in People Living with HIV during Respiratory Viral Infection and Vaccination
    (University of the Witwatersrand, Johannesburg, 2024) Motsoeneng, Boitumelo Madika; Moore, Penny
    There are approximately 39 million people living with human immunodeficiency virus (HIV) (PLWH) worldwide. Furthering our understanding of humoral immune responses to respiratory viral infection and vaccination in PLWH is essential for reducing the burden of these diseases, in high HIV prevalence settings, and informing vaccine implementation in this population. Influenza virus hemagglutinin (HA) stalk-specific antibodies have been associated with protection and shown to mediate Fc-mediated functions. This thesis describes HA stalk-specific antibody- dependent cellular phagocytosis (ADCP), cellular cytotoxicity (ADCC) and complement deposition (ADCD) between PLWH and people without HIV (PWOH) following immunization with a seasonal trivalent inactivated influenza vaccine (TIV). Irrespective of HIV status, ADCD was boosted while ADCC was not. ADCP was only enhanced in PWOH. The coordination of these functions differed by HIV status. Additionally, differences in the regulation of these HA stalk Fc responses by HIV infection was reported. Furthermore, ADCC was not associated with protection in this study. Pre- existing ADCP reduced the risk of influenza virus infection while TIV-induced ADCD provided protection against influenza-illness. Overall, PLWH have unique responses to TIV and HA stalk- specific ADCD correlated with protection following TIV. For SARS-CoV-2, antiretroviral treatment (ART)-naïve PLWH had reduced humoral responses to respiratory infection. The infecting variants D614G and Beta differentially triggered ADCC, ADCD and antibody-dependent cellular trogocytosis (ADCT). Regarding the kinetics, PLWH infected with D614G had delayed neutralization and ADCP while Beta infection delayed ADCT, regardless of HIV status. PLWH showed improved coordination between immune responses following respiratory infection. ChAdOx-1 nCoV-19 vaccination differed from infection in that PLWH had delayed IgG binding while neutralization and ADCP were not delayed, and ADCC was substantially enhanced than in PWOH. In conclusion, despite the delayed and differential kinetics, PLWH on ART developed equivalent responses to PWOH, supporting the rapid rollout of ART and SARS-CoV-2 vaccines to PLWH. This thesis highlights the need to include high-risk groups with different responses in future vaccination trials and also supports the assessment of novel correlates of protection for future vaccines. Overall, this thesis provided insights into the mechanisms required for protection against severe respiratory diseases and improved our understanding of vaccine-induced immunity in PLWH
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    Do governments have any prima facie duties to fund influenza vaccination (for the elderly in sa) and adults 65 years and above to vaccinate against influenza, respectively?
    (University of the Witwatersrand, Johannesburg, 2023) Sarangarajan, Ruach; Ewuoso, Cornelius
    In this dissertation, I draw on the thinking about solidarity, reciprocity, distributive justice, incompleteness and conviviality grounded in African philosophy broadly, including African ethics, African epistemology, African aesthetics, African metaphysics and African logic, to name a few, to argue that institutions, particularly the South African (SA) government, have a prima facie responsibility to fund the influenza vaccination for adults 65 years and above. Equally, I draw on the moral norms arising from the same values grounded in African philosophy to argue that adults 65 years old have a prima facie duty to vaccinate against influenza. These claims address three core issues relevant to fostering influenza vaccine access: availability, affordability and acceptability. While the former claim ensures that influenza vaccinations are affordable and available to the target population group, the latter underscores the obligation of adults 65 years and above to vaccinate to address acceptability issues. Although the dissertation focuses specifically on the South African government to defend its core thesis, I believe the arguments can reasonably be adapted to address the responsibilities of other African governments and older persons in other regions. Notably, these responsibilities are that the SA government should make influenza vaccines freely available for adults 65 years and above in public and private health facilities, provided financial allocation and their extant relationships allow for this. Additionally, the SA government has a responsibility to improve influenza vaccine procurement and availability in the country, preferably through increasing manufacturing capabilities. Furthermore, the dissertation argues that adults 65 years and above have a prima facie responsibility to vaccinate against influenza. Notably, adults 65 years and above have a duty of conviviality to act in ways that limit harm to them and others. This project is intrinsically valuable to promote epistemic justice, thereby contributing towards the decolonization of the global healthcare system. Moreover, this project has social significance in contributing to mitigation efforts against future public health challenges associated with population ageing in resource-limited developing African nations, wherein the impact of population transition will be most felt