Understanding the relationship between vaccination, vaccine-preventable diseases, and HIV infection among sub-Saharan African children

Adetokunboh, Olatunji Oluseyi (2019-04)

Thesis (PhD)--Stellenbosch University, 2019.

Thesis

ENGLISH SUMMARY : Numerous care and treatment guidelines pinpoint vaccination as a crucial preventive strategy for HIV-infected patients, but data regarding these vaccines among children living with HIV are still very scanty. There are knowledge gaps concerning the understanding of the mediators of vaccine protection, adverse effects and fundamental aspects of the epidemiology of various vaccine-preventable diseases. Likewise, there is also limited information on the determinants of vaccine non-uptake within the HIV-infected population, and on the association between maternal HIV status and the vaccination status of her HIV-exposed child. Further synthesis of all available evidence is required to provide reliable and easily accessible information for decision-makers and healthcare workers. We completed evidence synthesis of existing studies and secondary analyses of existing data sets using different research methods such as systematic review, meta-analysis, meta-regression and multivariable logistic regression models. We found that the burden of vaccine-preventable diseases is still high among HIV-infected and HIV-exposed children in sub-Saharan Africa. Several routine vaccines show possibilities for direct and indirect protection against various vaccine-preventable diseases among HIV-infected and HIV-exposed children. However, HIV-infected children are less likely to be protected against vaccine-preventable diseases when compared to non-exposed children. There is no significant difference in the uptake of the full series of three doses of diphtheria-tetanus-pertussis containing vaccines (DTP3) among infants of HIV-infected mothers and those of uninfected mothers in sub-Saharan Africa. Vaccination coverage for both HIV-exposed children and non-exposed children is still sub-optimal. Furthermore, individual and contextual factors such as maternal age, educational level, unemployment, and adult literacy level contributed significantly to non-uptake of DTP3 among the children of HIV-infected women across sub-Saharan Africa. The symptoms of acute respiratory infections show no statistical difference in the overall estimates between the children of HIV-infected mothers who were vaccinated with DTP3 and the ones who were not vaccinated. The data for episodes of diarrhoea were pooled together with resultant nil significant difference in the overall estimates between the children of HIV-infected mothers who were vaccinated with DTP3 and those not vaccinated. Many African countries also recorded high rates of respiratory infections and diarrhoeal diseases among both HIV-exposed and unexposed children. Residency in communities with high unemployment was an independent predictor of acute respiratory infections among immunised and HIV-exposed children while those born to women aged 15-24 or 25-34 years old were significantly more likely to develop diarrhoeal diseases. There is a need to address sub-optimal uptake of vaccines among HIV-exposed and non-exposed children. Epidemiological studies on vaccine-preventable diseases and the development of more efficacious vaccines are required for vaccine-preventable diseases studies with respect to HIV-infected and HIV-exposed uninfected children. The findings of this research would be useful in advocating for a more equitable share of healthcare resources especially for preventive services such as vaccination of both HIV-exposed and non-exposed children with subsequent reduction in the burden of vaccine-preventable diseases.

AFRIKAANSE OPSOMMING : Verskeie sorg- en behandelingsriglyne dui op inenting as ’n noodsaaklike voorkomingstrategie vir MIV-positiewe pasiënte. Tog is daar nog weinig data beskikbaar oor hierdie inentings onder kinders wat met MIV leef. Daar bestaan kennisleemtes in die begrip van die bemiddelaars van inentingsbeskerming, die nadelige gevolge van inenting, en fundamentele aspekte van die epidemiologie van verskeie siektes wat met inentings voorkom kan word. Eweneens is daar beperkte inligting oor die redes waarom die MIV-positiewe populasie nié van inenting gebruik maak nie, en die verband tussen die ma se MIV-status en die inentingstatus van haar MIV-blootgestelde kind. Verdere sintese van alle beskikbare bewyse word vereis om betroubare en maklik toeganklike inligting aan besluitnemers en gesondheidsorgwerkers te voorsien. In hierdie navorsing is die bewyse uit bestaande studies gesintetiseer en sekondêre ontledings van die bestaande datastelle onderneem. Hiervoor is verskillende navorsingsmetodes gebruik, waaronder stelselmatige oorsig, meta-ontleding, meta-regressie en meerveranderlike logistiese regressie. Die ontledings toon dat die las van inentingsvoorkombare siektes steeds hoog is onder MIV-positiewe én -blootgestelde kinders in Afrika suid van die Sahara. ’n Aantal roetine-inentings blyk MIV-positiewe en -blootgestelde kinders moontlike direkte sowel as indirekte beskerming teen ’n verskeidenheid inentingsvoorkombare siektes te bied. Tog is die waarskynlikheid dat MIV-positiewe kinders teen inentingsvoorkombare siektes ingeënt sal word kleiner as by nieblootgestelde kinders. Daar is geen beduidende verskil tussen die gebruik van die volle reeks van drie dosisse difterie-tetanus-pertussis-inentings (DTP3) onder die babas van MIV-positiewe ma’s en die babas van MIV-negatiewe ma’s in Afrika suid van die Sahara nie. Nietemin is inentingsdekking vir sowel MIV-blootgestelde as -nieblootgestelde kinders steeds suboptimaal. Daarbenewens het individuele en kontekstuele faktore, soos die ma se ouderdom, opvoedingsvlak, werkstatus en geletterdheidsvlak, ’n aansienlike invloed op die niegebruik van DTP3 onder die kinders van MIV-positiewe vroue in Afrika suid van die Sahara. Die simptome van akute respiratoriese infeksies toon geen statistiese verskil in algehele ramings tussen MIV-positiewe ma’s se kinders wat met DTP3 ingeënt is en kinders wat nié ingeënt is nie. Die data vir gevalle van diarree is saamgevoeg, en dui ook op geen beduidende verskil in algehele ramings tussen MIV-positiewe ma’s se kinders mét DTP3-inenting en diegene sónder sodanige inenting nie. Baie Afrikalande meld ’n hoë voorkoms van respiratoriese infeksies en diarreesiektes onder sowel MIV-blootgestelde as -nieblootgestelde kinders aan. Verblyf in gemeenskappe met hoë werkloosheidsyfers is ’n onafhanklike voorspeller van akute respiratoriese infeksies onder geïmmuniseerde en MIV-blootgestelde kinders, terwyl die kinders van vroue in die ouderdomskategorie 15–24 of 25–34 ’n aansienlik groter geneigdheid tot diarreesiektes toon. Die suboptimale gebruik van inentings onder MIV-blootgestelde en -nieblootgestelde kinders verg aandag. Meer studies oor inentingsvoorkombare siektes by MIV-positiewe en MIV-blootgestelde dog -negatiewe kinders word vereis met betrekking tot epidemiologie sowel as die ontwikkeling van doeltreffender entstowwe. Die bevindinge van hierdie navorsing sal nuttig wees om voorspraak te doen vir ’n billike toewysing van gesondheidsorghulpbronne aan voorkomende dienste, waaronder die inenting van sowel MIV-blootgestelde as -nieblootgestelde kinders, wat die las van inentingsvoorkombare siektes sal verlig.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/105873
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