Background Conflicting results of recent studies on the association between Helicobacter pylori (H. pylori) infection and the risk of insulin resistance and metabolic syndrome explored the need for updated meta-analysis on this issue. Therefore, this systematic review aimed to estimate the pooled effect of H. pylori infection on the risk of insulin resistance and metabolic syndrome. Methods To identify case–control studies and cohort studies evaluating the association of H. pylori infection with insulin resistance and metabolic syndrome, a comprehensive literature search was performed from international databases including Medline (PubMed), Web of Sciences, Scopus, EMBASE, and CINHAL from January 1990 until January 2021. We used odds ratio with its 95% confidence interval to quantify the effect of case–control studies and risk ratio with its 95% CI for the effect of cohort studies. Results 22 studies with 206,911 participants were included for meta-analysis. The pooled estimate of odds ratio between H. pylori infection and metabolic syndrome in case–control studies was 1.19 (95% CI 1.05–1.35; I2 = 0%), and in cohort studies, the pooled risk ratio was 1.31 (95% CI 1.13–1.51; I2 = 0%). Besides, case–control studies showed the pooled odds ratio of 1.54 (95% CI 1.19–1.98; I2 = 6.88%) for the association between H. pylori infection and insulin resistance. Conclusion In this meta-analysis, the results showed that there was a possibility of metabolic syndrome and insulin resistance in case of H. pylori infection.

Background Covid-19 has been one of the major concerns around the world in the last 2 years. One of the challenges of this disease has been to determine its prevalence. Conflicting results of the serology test in Covid explored the need for an updated meta-analysis on this issue. Thus, this systematic review aimed to estimate the prevalence of global SARS-CoV-2 serology in different populations and geographical areas. Methods To identify studies evaluating the seroprevalence of SARS-CoV-2, a comprehensive literature search was performed from international databases, including Medline (PubMed), Web of Sciences, Scopus, EMBASE, and CINHAL. Results In this meta-analysis, the results showed that SARS-CoV-2 seroprevalence is between 3 and 15% worldwide. In Eastern Mediterranean, the pooled estimate of seroprevalence SARS-CoV-2 was 15% (CI 95% 5–29%), and in Africa, the pooled estimate was 6% (CI 95% 1–13%). In America, the pooled estimate was 8% (CI 95% 6–11%), and in Europe, the pooled estimate was 5% (CI 95% 4–6%). Also the last region, Western Pacific, the pooled estimate was 3% (CI 95% 2–4%). Besides, we analyzed three of these areas separately. This analysis estimated the prevalence in subgroups such as study population, diagnostic methods, sampling methods, time, perspective, and type of the study. Conclusion The present meta-analysis showed that the seroprevalence of SARS-CoV-2 has been between 3 and 15% worldwide. Even considering the low estimate of this rate and the increasing vaccination in the world, many people are still susceptible to SARS-CoV-2.

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