Fractional dosing to improve vaccination coverage, vaccine hesitancy, and cost-effectiveness in Africa: a systematic review

Background The major challenges of vaccination programs are notably coverage in the target population, vaccine hesitancy, and cost-effectiveness. A vaccination strategy with fractional doses is a dose-saving strategy to address current vaccine shortages. Herein, we aimed to review the literature on administering fractional vaccine doses in Africa. Methods A methodical search of PubMed was conducted to identify articles published up till March 31, 2023. Peer-reviewed studies were selected for inclusion if they focused on studies that described the use of fractional doses of vaccines and were conducted in any of the 54 African countries. Results Findings from eleven eligible studies were analyzed. Studies were from the Democratic Republic of the Congo, Gambia, Ghana, Kenya, South Africa, and Uganda. They covered five vaccines including the yellow fever vaccine (n=3; 27.3%), inactivated poliovirus vaccine (n=3; 27.3%), meningococcal A/C/Y/W135 vaccine (n=2; 18.2%), Haemophilus influenzae type b vaccine (n=2; 18.2%), and malaria vaccine (n=1; 9.1%). Fractionated doses used most often consist of one-fifth of the standard dose (n=8; 72.7%). Regarding immunogenicity/efficacity, eight of ten studies that addressed immunogenicity suggest that immune responses to the fractional dose vaccines were comparable to that of the standard dose vaccines and resulted in higher antibody titers. Regarding safety, all of the eight studies that addressed the safety of fractional doses in Africa, suggest that safety and tolerability data of fractional dosing were favorable compared to full dose regimen. Conclusion Fractional dosing may be considered to address the availability and acceptability of certain vaccines while maintaining protection. This strategy also has the potential advantage of reducing the cost of vaccination programs, vaccine antigen overload, and vaccine side effects. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement No ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.