Causes of impaired oral vaccine efficacy in developing countries

• Authors: Edward P. K. Parker, Imperial College London; Sasirekha Ramani, Baylor College of Medicine; Benjamin Lopman, Emory University; James A. Church, Queen Mary University London; Miren Iturriza-Gomara, University of Liverpool; Andrew J. Prendergast, Queen Mary University London; Nicholas C. Grassly, Imperial College London
• Journal Title: Future Microbiology
• Volume: Volume 13, Number 1
• Publisher: Future Medicine Ltd. | 2018-01-01, Pages 97-118
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.2217/fmb-2017-0128
• Subjects: Biology, Microbiology; Biology, Virology; Sociology, Social Structure and Development; Health Sciences, Epidemiology
• Keywords: Science & Technology; Life Sciences & Biomedicine; Microbiology; cholera; enteropathy; histo blood group antigens; immunogenicity; malnutrition; microbiota; oral vaccines; poliovirus; rotavirus; Human rotavirus vaccine; Randomized controlled trial; Placebo-controlled trial; Vitamin-A supplements; Live cholera vaccine; Blood-group antigens; Killed bivalent 01; Breast-fed; 1st two years; Poliovirus vaccine

Abstract

Oral vaccines are less immunogenic when given to infants in low-income compared with high-income countries, limiting their potential public health impact. Here, we review factors that might contribute to this phenomenon, including transplacental antibodies, breastfeeding, histo blood group antigens, enteric pathogens, malnutrition, microbiota dysbiosis and environmental enteropathy. We highlight several clear risk factors for vaccine failure, such as the inhibitory effect of enteroviruses on oral poliovirus vaccine. We also highlight the ambiguous and at times contradictory nature of the available evidence, which undoubtedly reflects the complex and interconnected nature of the factors involved. Mechanisms responsible for diminished immunogenicity may be specific to each oral vaccine. Interventions aiming to improve vaccine performance may need to reflect the diversity of these mechanisms.