The research process
| Search strategy | A systematic literature search of both scientific and economic databases was conducted according to the PRISMA requirements (Preferred Reporting Items or Systematic reviews and Meta-Analyses; Moher et al., 2009). Figure 1 shows the different phases of the search process |
| Web of Science and PubMed databases were systematically searched and the following restrictions were applied: English was the only language selected; the dates of the publications ranged from January 1, 2001 to July 15, 2021; only peer-reviewed articles were included; only studies related to LMICs were included, due to the research question we intend to address. Moreover, articles pertaining to non-humans, abstract-only papers as preceding papers, conference, editorial or articles without available full text available were excluded. The list of excluded studies is available upon request | |
| The search was preformed using appropriate text words and thesaurus terms for papers relating to the costs of immunization program in LMICs, particularly in sub-Saharan Africa. As for keywords, for both databases, we combined “vaccination cost/s”, “immunization cost/s” and “vaccine cost categories” with each of the following research strings: “Africa”, “sub-Saharan Africa” and “LMICs”. Thus, no search was performed using one keyword only, since our research question concerns the introduction of a vaccine in low-middle income countries and, in particular, in sub-Saharan Africa | |
| We collected all references in a single file for each database (2.269 references for PubMed and 848 for Web of Science). After merging the references in a unique file, 481 duplicates were removed. The titles first and the abstracts afterward of each reference were screened for relevance by the authors, who judged the relevance of the abstract if the title was found to be relevant. The authors worked independently and then the references screened were collected and compared. The overlapping references were selected to be considered for the next step, the analysis of the full text. The non-overlapping references were discussed and a common final decision was reached. Our search strategy returned 441 articles to be screened for full-text review. We excluded 411 articles since they were not relevant for the purpose of the present study and/or they did not provide quantitative reliable information about the costs of introducing a vaccine in poor countries. We were left with 30 articles eligible for our study. The references of the 30 selected articles were carefully screened and so doing 4 more contributions were selected to be included | |
| Due to the comprehensive approach this study aims at embracing, by providing quantitative information on different cost categories in order to cover the different phases required by the vaccine introduction, searches were also undertaken by hand focusing on references from identified papers, authors' own collections and review articles. Google and the bibliography of the main international agencies (as WHO, GAVI, UNICEF etc.), as well as reports from the World Bank, were searched for the relevant grey literature and 5 crucial contributions were included | |
| Study outcomes | Data were extracted and stored in an Excel sheet containing the economic information reported in each publication, on the basis of their availability. Variables collected included article information (title, authors, year and journal of publication) and economic quantitative information on the costs of the immunization programs |
| Search strategy | A systematic literature search of both scientific and economic databases was conducted according to the PRISMA requirements (Preferred Reporting Items or Systematic reviews and Meta-Analyses; |
| Web of Science and PubMed databases were systematically searched and the following restrictions were applied: English was the only language selected; the dates of the publications ranged from January 1, 2001 to July 15, 2021; only peer-reviewed articles were included; only studies related to LMICs were included, due to the research question we intend to address. Moreover, articles pertaining to non-humans, abstract-only papers as preceding papers, conference, editorial or articles without available full text available were excluded. The list of excluded studies is available upon request | |
| The search was preformed using appropriate text words and thesaurus terms for papers relating to the costs of immunization program in LMICs, particularly in sub-Saharan Africa. As for keywords, for both databases, we combined “vaccination cost/s”, “immunization cost/s” and “vaccine cost categories” with each of the following research strings: “Africa”, “sub-Saharan Africa” and “LMICs”. Thus, no search was performed using one keyword only, since our research question concerns the introduction of a vaccine in low-middle income countries and, in particular, in sub-Saharan Africa | |
| We collected all references in a single file for each database (2.269 references for PubMed and 848 for Web of Science). After merging the references in a unique file, 481 duplicates were removed. The titles first and the abstracts afterward of each reference were screened for relevance by the authors, who judged the relevance of the abstract if the title was found to be relevant. The authors worked independently and then the references screened were collected and compared. The overlapping references were selected to be considered for the next step, the analysis of the full text. The non-overlapping references were discussed and a common final decision was reached. Our search strategy returned 441 articles to be screened for full-text review. We excluded 411 articles since they were not relevant for the purpose of the present study and/or they did not provide quantitative reliable information about the costs of introducing a vaccine in poor countries. We were left with 30 articles eligible for our study. The references of the 30 selected articles were carefully screened and so doing 4 more contributions were selected to be included | |
| Due to the comprehensive approach this study aims at embracing, by providing quantitative information on different cost categories in order to cover the different phases required by the vaccine introduction, searches were also undertaken by hand focusing on references from identified papers, authors' own collections and review articles. Google and the bibliography of the main international agencies (as WHO, GAVI, UNICEF etc.), as well as reports from the World Bank, were searched for the relevant grey literature and 5 crucial contributions were included | |
| Study outcomes | Data were extracted and stored in an Excel sheet containing the economic information reported in each publication, on the basis of their availability. Variables collected included article information (title, authors, year and journal of publication) and economic quantitative information on the costs of the immunization programs |
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