Influenza: Diabetes as a risk factor for severe related-outcomes and the effectiveness of vaccination in diabetic population. A meta-analysis of observational studies.

AIMS: In order to better define the need for influenza vaccination in people with diabetes (DM), we collected all available evidence on the effect of DM as a risk factor for complications of both seasonal and pandemic influenza, and on the specific effectiveness of vaccines in patients with DM. DATA SYNTHESIS: Two distinct systematic searches on MEDLINE, Cochrane, ClinicalTrials.gov and Embase databases were performed, one for each metanalysis, collecting all observational studies and randomized clinical trials performed on humans up to May 31st, 2022. We retrieved 34 observational studies comparing risk for influenza complications in people with or without diabetes, and 13 observational studies assessing vaccine effectiveness on preventing such complications. Mortality for influenza and hospitalization for influenza and pneumonia resulted significantly higher in individuals with versus without DM, both when unadjusted and adjusted data are analyzed. In diabetic individuals vaccinated for influenza overall hospitalization, hospitalization for influenza or pneumonia and overall mortality are significantly lower in comparison with not vaccinated DM subjects, both when unadjusted and adjusted data were analyzed. CONCLUSION: This systematic review and meta-analysis shows that: 1) influenza is associated with more severe complications in diabetic versus not diabetic individuals and 2) influenza vaccination is effective in preventing clinically relevant outcomes in adults with DM with a NNT (number needed to treat) of 60, 319, and 250 for all-cause hospitalization, specific hospitalization, and all-cause mortality, respectively. The identification of diabetic patients as the target of vaccination campaigns for influenza appears to be justified by available clinical evidence.

Diabetes as a risk factor for pneumococcal disease and severe related outcomes and efficacy/effectiveness of vaccination in diabetic population. Results from meta-analysis of observational studies.

AIMS: To collect all available evidence on the effect of diabetes mellitus (DM) as a risk factor for pneumococcal disease incidence and related complications, and on the efficacy/effectiveness of vaccines in patients with DM. METHODS: Two distinct systematic searches on MEDLINE, Cochrane, ClinicalTrials.gov and EMBASE databases were performed, one for each meta-analysis, collecting all observational (cohort and case-control) studies and randomized clinical trials performed on humans up to June 1st, 2023. RESULTS: We retrieved 36 observational studies comparing risk for pneumococcal disease and related complications in people with or without DM, and 11 studies (1 randomized clinical trial and 10 observational studies) assessing conjugated and polysaccaridic vaccines efficacy/effectiveness on preventing such outcomes. People with DM were at higher risk for Invasive Pneumococcal Disease (unadjusted OR 2.42 [2.00; 2.92]); Case-Fatality Rate (unadjusted OR 1.61 [1.25; 2.07], Pneumococcal pneumonia (unadjusted OR 2.98 [2.76; 3.22), and Intensive care unit admission for pneumococcal disease (unadjusted OR 2.09 [1.20; 3.66]). In diabetic individuals vaccinated with conjugated vaccine, incidence of pneumonia specific for vaccine type in a clinical trial (OR 0.237 [0.008; 0.704]), and hospitalization for overall pneumonia during the year following the polysaccharide vaccination in observational studies (unadjusted OR 0.63 [0.45-0.89]) were significantly lower in comparison with unvaccinated DM subjects, with no significant differences for other outcomes. CONCLUSIONS: People with diabetes mellitus are at higher risk for less favourable course of pneumococcal disease and should be therefore targeted in vaccination campaigns; more evidence needs to be collected on vaccination outcomes in people with diabetes.

Efficacy and effectiveness of Herpes zoster vaccination in adults with diabetes mellitus: a systematic review and meta-analysis of clinical trials and observational studies.

AIM: The risk for Herpes zoster (HZ) and its complications is higher in people with diabetes mellitus (DM). Our aim is to assess efficacy and effectiveness of the currently available live-attenuated zoster vaccine (LZV) and recombinant zoster vaccine (RZV) in adults with DM. METHODS: A Systematic Review and Meta-analysis of clinical trials and observational studies comparing incidence of HZ and its complications in vaccinated and unvaccinated people with DM was performed, on PubMed, Cochrane, Clinical Trials.gov and Embase databases, up to January 15th, 2023. Risk of bias was assessed through the Cochrane Collaboration tool and the Newcastle-Ottawa Scale. The protocol was registered on the PROSPERO website (CRD42022370705). RESULTS: Only three observational studies reported LZV efficacy and effectiveness in people with DM. A lower risk for HZ infection (MH-OH Ratio 95% CI = 0.52 [0.49, 0.56] was observed, for unadjusted analysis, and 0.51 [0.46, 0.56] for adjusted analysis, both with P < 0.00001 and no heterogeneity). No data on LZV safety were reported. A pooled analysis of two trials comparing RZV and placebo, showed a reduced risk for HZ incidence: (95% CI Odds Ratio: 0.09 [0.04-0.19]), with no difference in severe adverse events and mortality. CONCLUSIONS: In our meta-analysis of three observational studies LZV showed a 48% effectiveness in reducing HZ incidence in adults with diabetes whereas in a pooled analysis of two RCTs, RZV showed a 91% efficacy. No data are available on the effects of vaccination on the incidence and severity of HZ-related complications among subjects with diabetes.