Objectives This meta-analysis evaluated the Efficacy and Effectiveness of several COVID-19 vaccines, including AstraZeneca, Pfizer, Moderna, Bharat, and Johnson & Johnson, to better estimate their immunogenicity, benefits, or side effects. Methods Studies reporting the Efficacy and Effectiveness of COVID-19 vaccines from November 2020 to April 2022 were included. The pooled Effectiveness/Efficacy with a 95% confidence interval (95% CI) with Metaprop order was calculated. The results were presented in forest plots. Predefined subgroup analyses and sensitivity analyses were also performed. Results A total of twenty articles were included in this meta-analysis. After the first dose of the vaccine, the total effectiveness of all COVID-19 vaccines in our study was 71% (95% CI 0.65, 0.78). The total effectiveness of vaccines after the second dose was 91% (95% CI 0.88, 0.94)). The total efficacy of vaccines after the first and second doses was 81% (95% CI 0.70, 0.91) and 71% (95% CI 0.62, 0.79), respectively. The effectiveness of the Moderna vaccine after the first and second dose was the highest among other studied vaccines ((74% (95% CI, 0.65, 0.83) and 93% (95% CI, 0.89, 0.97), respectively). The highest first dose overall effectiveness of the studied vaccines was against the Gamma variant (74% (95% CI, 0.73, 0.75)), and the highest effectiveness after the second dose was observed against the Beta variant (96% (95% CI, 0.96, 0.96)). The Efficacy for AstraZeneca and Pfizer vaccines after the first dose was 78% (95% CI, 0.62, 0.95) and 84% (95% CI, 0.77, 0.92), respectively. The second dose Efficacy for AstraZeneca, Pfizer, and Bharat was 67% (95% CI, 0.54, 0.80), 93% (95% CI, 0.85, 1.00), and 71% (95% CI, 0.61, 0.82), respectively. The overall efficacy of first and second dose vaccination against the Alfa variant was 84% (95% CI, 0.84, 0.84) and 77% (95% CI, 0.57, 0.97), respectively, the highest among other variants. Conclusion mRNA-based vaccines against COVID-19 showed the highest total efficacy and effectiveness than other vaccines. In general, administering the second dose produced a more reliable response and higher effectiveness than a single dose.

This meta-analysis aimed to determine the prevalence, symptoms, and outcomes of COVID-19 in the elderly with Parkinson’s disease (PD) by searching in the international databases of PubMed, Scopus, Web of Sciences, and EMBASE using the keywords of “COVID-19” and “Parkinson’s.” All articles related to Parkinson's disease and COVID-19 from January 2019 to October 20, 2021 were reviewed. The STATA software was used for analysis. A total of 20 articles were selected for data extraction in this meta-analysis, of which ten were cross-sectional studies (to determine the prevalence), five case–control studies, and five cohort studies (to examine the association). The results of the meta-analysis showed the prevalence of COVID-19 in patients with PD was 1.06% (95% CI 1.03–1.1%; P = 0.02), and the prevalence of their hospitalization due to COVID-19 was 0.98% (95% CI: 0.95–1.02%; P = 0.00). Also, the prevalence of depression and anxiety during the pandemic in this group was 46% (95% CI 29–64%; P = 0.00) and 43% (95% CI: 24–63%; P = 0.00), respectively. The prevalence of tremor and sleep problems were higher than those of other symptoms in the studied population. According to the results, there was no significant difference in the risk of COVID-19 infection between Parkinson's patients and healthy people. In other words, the risk of COVID-19 infection was equal in both groups (RR = 1.00 (CI 95% 0.77–1.30%; P = 0.15)). The results showed mortality and hospitalization rates of the elderly with Parkinson's disease were not significantly different from those of the general population during the COVID-19 pandemic. Also, the symptoms of Parkinson’s disease and mental disorders increased during the COVID-19 pandemic. So, designing and developing more specific studies, like cohort studies, with large sample size is required for assessing these associations.

This meta-analysis aimed to determine the pooled association between polycystic ovary syndrome (PCOS), hypothyroidism, and fibrocystic breast changes. We searched important databases, including PubMed (Medline), Scopus, Web of Science, and Embase to retrieve all relevant studies published from 1990 to April 2021. The bias risk of selected articles was assessed based on the JBI checklist. Our search strategy yielded a total of 487 articles from the international databases. After screening their full-texts, 6 articles met the inclusion criteria and were considered for meta-analysis. The effect of PCOS on the incidence of fibrocystic breast changes was 2.49 (95% CI 1.85–3.34). Also, the effect of hypothyroidism on the incidence of fibrocystic breast changes was 1.90 (95% CI 0.92–3.93). The results showed that women with PCOS were at higher risks to develop fibrocystic breast changes.

Introduction:The aim of this review was to combine the results of published cohort studies to determine the exact association between chronic liver disorders, and the severe form of COVID-19, and its associated complications. Methods: This meta-analysis employed a keyword search (COVID-19 and chronic liver disorders) using PubMed (Medline), Scopus, Web of Sciences, and Embase (Elsevier). All articles related from January 2019 to May 2022 were reviewed. The STATA software was used for analysis. Results: The risk of death in COVID-19 patients with chronic liver disorders was higher than in ones without the chronic liver disease (RR: 1.52; CI 95%: 1.46-1.57; I 2 : 86.14%). Also, the risk of acute respiratory distress syndrome (ARDS) and hospitalization in COVID-19 patients with chronic liver disorders was higher than in ones without the chronic liver disease ([RR: 1.65; CI 95%: 1.09-2.50; I 2 : 0.00%] and [RR: 1.39; CI 95%: 1.23-1.58; I 2 : 0.20%]). Also, the meta-analysis showed cough, headache, myalgia, nausea, diarrhea, and fatigue