The prevalence, incidence, and characteristics of bacterial infections in patients infected with severe acute respiratory syndrome coronavirus 2 are not well understood and have been raised as an important knowledge gap. Therefore, our study focused on the most common opportunistic infections/secondary infections/superinfections in coronavirus disease 2019 (COVID-19) patients. This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Eligible studies were identified using PubMed/Medline since inception to June 25, 2021. Studies meeting the inclusion criteria were selected. Statistical analysis was conducted in Review Manager 5.4.1. A random-effect model was used when heterogeneity was seen to pool the studies, and the result was reported as inverse variance and the corresponding 95% confidence interval. We screened 701 articles comprising 22 cohort studies which were included for analysis. The pooled prevalence of opportunistic infections/secondary infections/superinfections was 16% in COVID-19 patients. The highest prevalence of secondary infections was observed among viruses at 33%, followed by bacteria at 16%, fungi at 6%, and 25% among the miscellaneous group/wrong outcome. Opportunistic infections are more prevalent in critically ill patients. The isolated pathogens included Epstein-Barr virus, Pseudomonas aeruginosa , Escherichia coli , Acinetobacter baumannii , Hemophilus influenza , and invasive pulmonary aspergillosis. Large-scale studies are required to better identify opportunistic/secondary/superinfections in COVID-19 patients.

Background The clinical impact of the influenza vaccination on cardiovascular outcomes in people with established cardiovascular disease (CVD) is still debated. Aim The aim of this meta-analysis was to estimate the effect of influenza vaccination on cardiovascular and cerebrovascular outcomes among patients with established CVD. Methods We systematically searched all electronic databases from inception until 15 April 2022. Primary clinical outcomes were all-cause mortality (ACM), and major adverse clinical events (MACE). Secondary endpoints were heart failure, myocardial infarction, CV mortality, and stroke. Results Eighteen articles (five randomized trials and thirteen observational studies), with a total of 22,532,165 patients were included in the analysis. There were 217,072 participants included in the high cardiovascular risk or established CVD population (vaccinated n = 111,073 and unvaccinated n = 105,999). The mean age of the patients was 68 years old, without any difference between groups (69 vs 71) years. At mean follow-up of 1.5 years, vaccinated group was associated with lower risk for all-cause mortality [HR, 0.71(95%CI, 0.63-0.80), p < 0.001], MACE [HR, 0.83(95%CI:0.72-0.96), p = 0.01], CV mortality [HR, 0.78(95%CI:0.68-0.90), p < 0.001] and myocardial infarction [HR, 0.82(95%CI:0.74-0.92), p < 0.001] compared to unvaccinated group. While incidence of stroke [HR, 1.03 (95%CI, 0.92-1.06), p = 0.61] and heart failure [HR, 0.74 (95%CI, 0.51-1.08), p = 0.12] did not differ between the two groups. Conclusion Influenza vaccination reduced major adverse clinical events, all-cause mortality, CV mortality and myocardial infarction. These highlighted the importance of influenza vaccination in established CVD or high cardiovascular risk.

Various studies have suggested the possible cardiovascular (CV) protective effects of the pneumococcal vaccine (PV). Therefore, we conducted a meta-analysis to assess the association between recipients of PV with mortality and CV outcomes among patients with and without established cardiovascular disease. We performed a systematic literature search in PubMed, Embase, and Scopus for studies evaluating the effect of PV on mortality and CV outcomes. A total of 15 studies with 347,444 patients were included in the meta-analysis: 111,784 patients received PV (32%) and 235,660 patients were in the unvaccinated group (68%). Recipients of PV were associated with decreased all-cause mortality (HR, 0.76 (95% CI: 0.66 to 0.87), p < 0.001). PV was associated with a decrease in the incidence of myocardial infarction (MI) (HR, 0.73 (95% CI: 0.56–0.96), p = 0.02), without significant reduction in CV mortality (HR, 0.87 (95% CI: 0.72–1.07), p = 0.18) and stroke (HR, 1.01 (95% CI: 0.93–1.10), p = 0.82). Our study found PV was associated with decreased risk of all-cause mortality and MI. Future RCTs will be necessary to confirm benefits associated with receipt of PV.