Frequent inappropriate use of unweighted summary statistics in systematic reviews of pathogen genotypes or genogroups

•There is a concern about the quality of the report methods in epidemiological systematic reviews of pathogen genotypes or genogroups.•Our study found three method types used to summarize genotypes or genogroups, including (1) meta-analysis, which conducted weighted pooling analysis; (2) unweighted analysis of the study-level measures; and (3) systematic review only, without any data pooling.•The meta-analytic articles have significantly higher quality scores (measured by Assessment of Multiple Systematic Reviews, Preferred Reporting Items for Systematic Reviews and Meta-analyses, and Risk Of Bias In Systematic reviews tools) compared with those that used summary statistics or a systematic review without pooling.•Although the frequent use of summary statistics, the meta-analysis has become the most qualified method used in epidemiological studies of pathogen genotypes or genogroups.