Browsing by Author "Nassuuna, Jacent"

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    Effect of intensive treatment for schistosomiasis on immune responses to vaccines among rural Ugandan island adolescents: randomised controlled trial protocol A for the ‘POPulation differences in VACcine responses’ (POPVAC) programme
    (BMJ open, 2021-02-16) Nkurunungi, Gyaviira; Zirimenya, Ludoviko; Nassuuna, Jacent; Niwagaba, Emmanuel; Amongi, Susan
    Several licensed and investigational vaccines have lower efficacy, and induce impaired immune responses, in low-income versus high-income countries and in rural, versus urban, settings. Understanding these population differences is essential to optimising vaccine effectiveness in the tropics. We suggest that repeated exposure to and immunomodulation by chronic helminth infections partly explains population differences in vaccine response.
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    Pre-vaccination Schistosoma mansoni and hookworm infections are associated with altered vaccine immune responses: a longitudinal analysis among adolescents living in helminth-endemic islands of Lake Victoria, Uganda
    (Frontiers in Immunology, 2024-08-29) Natukunda, Agnes; Zirimenya,Ludoviko; Nkurunungi, Gyaviira; Nassuuna, Jacent
    Variations in vaccine responses have been observed between populations. A role for helminth infections has been proposed due to their immunomodulatory properties. In a secondary analysis of data from a randomised trial assessing effects of anthelminthic treatment on vaccine responses, we examined associations between helminth infections at baseline prior to vaccine administration, and vaccine responses among adolescents (9-17 years) in Koome Islands, Lake Victoria, Uganda.
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    The effect of helminth infection on vaccine responses in humans and animal models: A systematic review and meta-analysis
    (Parasite Immunology, 2022-06-17) Natukunda, Agnes; Zirimenya, Ludoviko; Nassuuna, Jacent; Nkurunungi, Gyaviira; Elliott, Alison M.; Webb, Emily L.
    Vaccination has potential to eliminate infectious diseases. However, parasitic infections such as helminths may hinder vaccines from providing optimal protection. We reviewed existing literature on the effects of helminth infections and their treatment on vaccine responses in humans and animals. We searched literature until 31 January 2022 in Medline, EMBASE, Global health, Scopus, and Web of science; search terms included WHO licensed vaccines and human helminth types. Standardized mean differences (SMD) in vaccine responses between helminth infected and uninfected or anthelminthic treated and untreated individuals were obtained from each study with suitable data for meta-analysis, and combined using a random effects model. Analysis was stratified by whether helminth exposure was direct or prenatal and by vaccine type. This study is registered with PROSPERO (CRD42019123074). Of the 4402 articles identified, 37 were included in the review of human studies and 24 for animal experiments. For human studies, regardless of vaccine type, overall SMD for helminth uninfected/treated, compared to infected/untreated, was 0.56 (95% CI 0.04–1.07 and I2 = 93.5%) for direct helminth exposure and 0.01 (95% CI −0.04 to 0.07 and I2 = 85.9%) for prenatal helminth exposure. Effects of anthelminthic treatment were inconsistent, with no overall benefit shown. Results differed by vaccine type, with responses to live vaccines most affected by helminth exposure. For animal studies, the most affected vaccine was BCG. This result indicates that helminth-associated impairment of vaccine responses is more severe for direct, than for prenatal, helminth exposure. Further research is needed to ascertain whether deworming of individuals before vaccination may help improve responses.
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    The effect of intensive praziquantel administration on vaccine-specific responses among schoolchildren in Ugandan schistosomiasis-endemic islands (POPVAC A): an open-label, randomised controlled trial
    (The Lancet Global Health, 2024-11-23) Nkurunungi, Gyaviira; Nassuuna, Jacent; Natukunda, Agnes; Walusimbi, Bridgious
    Vaccine responses differ between populations and are often impaired in rural and low-income settings. The reasons for this are not fully understood, but observational data suggest that the immunomodulating effects of parasitic helminths might contribute. We hypothesised that Schistosoma mansoni infection suppresses responses to unrelated vaccines, and that suppression could be reversed—at least in part—by intensive praziquantel administration.