Prevalence of human influenza virus in Iran: Evidence from a systematic review and meta-analysis

This systematic review and meta-analysis was conducted to consolidate the information on the prevalence of the human influenza virus, including H1N1 and H3N2 as well as B-type influenza across Iran from 2000 to December 2016. The literature search was based on keywords including "influenza and Iran", "human influenza", "prevalence", "relative frequency", "incidence", and "drug" in MEDLINE (PubMed), Web of Science, Scopus, ScienceDirect, the Iranian Research Institute for Information Science and Technology (IranDoc), the Regional Information Centre for Science & Technology (RICeST), and the Scientific Information Database (SID). The literature search revealed 25 prevalence and seven drug resistance studies. In order to investigate the publication bias among studies, funnel plots and Egger's test were used. Additionally, the statistical tests of I², Chi², and Tau² were computed, and the results were visualized with forest plots. A high level of I² and Chi² were obtained among studies, which are representative of the high variation and remarkable heterogeneity between studies. This may be because of various methodologies applied in the studies such as study design, age groups, and different populations. The prevalence of influenza H1N1, H3N2, and B in Iran have not yet been well evaluated. The heterogeneity among studies reveals that more attention should be paid to considering various factors, including gender, population size, and underlying conditions.