br Methods We searched PubMed and Medline

Methods We searched PubMed and Medline for papers on revaccination with BCG, MV, OPV and smallpox vaccine and mortality/death. The literature searches are explained in Supplementary Figs. 1–4. WHO recently organised a major review of the potential nonspecific effects of BCG pteryxin and MV on child survival (Higgins et al., 2014; Strategic Advisory Group of Experts on Immunization, 2014). Since this review was also taken into consideration, it is unlikely that there would be additional studies on BCG and MV that we have not found. It will be seen (Supplementary Figs. 3–4) that there were few studies on revaccination with OPV or smallpox vaccine. Interventions may interact; thus to determine the effect of revaccination with a live vaccine we tried to eliminate the effect of other interventions. For example, many studies have suggested that DTP has negative effects on child survival when given after a live vaccine (Roth et al., 2010; Aaby et al., in press; Benn and Aaby, 2012). We recently reviewed the available data and found, in studies with registration of vaccination status and prospective follow-up, that DTP given as the most recent vaccination was associated with two-fold higher mortality than not being DTP-vaccinated (Aaby et al., in press). We therefore censored children who were likely to receive DTP in the studies of revaccination with BCG or MV. In one RCT (Aaby et al., 2010), many children had previously received neonatal vitamin A supplementation (NVAS) and NVAS neutralised the beneficial effect of MV (Benn et al., 2014). NVAS is unlikely to become official WHO policy as it has shown a negative effect on survival in African studies (Benn et al., 2015) and we have restricted the analysis to those who did not receive NVAS. Restrictions have been explained in footnotes to the tables.
Results
Discussion
Conclusion
Contributions CSB and PA developed the hypothesis (Aaby et al., 2014) and all authors further developed the idea and reviewed the literature.
Conflict of Interest
Ethical Approval
Funding
Role of the Funding Source
Data Sharing
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