Effect of Influenza Vaccination in Preventing Laboratory-Confirmed Influenza Hospitalization in Patients With Diabetes Mellitus

Sex-Specific Immune Responses to Seasonal Influenza Vaccination in Diabetic Individuals: Implications for Vaccine Efficacy

Seasonal influenza vaccination has different implications on the immune response depending on the comorbidities. Diabetes is one such critical disease that increases the patient's susceptibility to influenza and suppresses vaccine efficacy and immunity. The sex of the individuals also plays a definitive role in the immune responses to both the vaccine and the infection. This study aims to understand the efficacy of the seasonal vaccine against influenza in diabetic groups and undergoing immune mechanisms in different sexes (females and males). In this study, we are reporting about a switching of the immune response of the infected and vaccinated diabetic females towards stronger Th1/Th17 responses with suppressed humoral immunity. They show increased cDC1, enhanced proinflammatory activities within T cells, CD8T activation, Th17 proliferation, and the majority of IgG2 antibody subtypes with reduced neutralization potential. Males with diabetes exhibit enhanced humoral Th2-immunity than the nondiabetic group. They exhibit higher cDC2, and DEC205 levels within them with an increase in plasma B lymphocytes, higher IgG1 subtypes in plasma cells, and influenza-hemagglutinin-specific IgG titer with stronger virus neutralization potential. Males with diabetes recovered better than the females as observed from the changes in their body weight. This study highlights the critical immune mechanisms and sex-specific swapping of their preferred immune response pathways against influenza after vaccination during diabetes. We propose a need for a sex-specific customized vaccine regimen to be implemented against influenza for individuals having diabetes to exploit the manifested strength and weakness in their protective immunity.

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.

Age Differences in Comorbidities, Presenting Symptoms, and Outcomes of Influenza Illness Requiring Hospitalization: A Worldwide Perspective From the Global Influenza Hospital Surveillance Network

Background

The Global Influenza Hospital Surveillance Network (GIHSN) was established in 2012 to conduct coordinated worldwide influenza surveillance. In this study, we describe underlying comorbidities, symptoms, and outcomes in patients hospitalized with influenza.

Methods

Between November 2018 and October 2019, GIHSN included 19 sites in 18 countries using a standardized surveillance protocol. Influenza infection was laboratory-confirmed with reverse-transcription polymerase chain reaction. A multivariate logistic regression model was utilized to analyze the extent to which various risk factors predict severe outcomes.

Results

Of 16 022 enrolled patients, 21.9% had laboratory-confirmed influenza; 49.2% of influenza cases were A/H1N1pdm09. Fever and cough were the most common symptoms, although they decreased with age (P < .001). Shortness of breath was uncommon among those <50 years but increased with age (P < .001). Middle and older age and history of underlying diabetes or chronic obstructive pulmonary disease were associated with increased odds of death and intensive care unit (ICU) admission, and male sex and influenza vaccination were associated with lower odds. The ICU admissions and mortality occurred across the age spectrum.

Conclusions

Both virus and host factors contributed to influenza burden. We identified age differences in comorbidities, presenting symptoms, and adverse clinical outcomes among those hospitalized with influenza and benefit from influenza vaccination in protecting against adverse clinical outcomes. The GIHSN provides an ongoing platform for global understanding of hospitalized influenza illness.

Influenza Prevalence and Vaccine Efficacy among Diabetic Patients in Qatar

Seasonal influenza viruses may lead to severe illness and mortality in patients with comorbidities, including Diabetes Mellitus (DM). Vaccination against influenza in DM patients may reduce influenza incidence and severity. Before the emergence of the COVID-19 pandemic, influenza infections were the most prevalent respiratory infections in Qatar. Still, reports about influenza prevalence and vaccine efficacy in DM patients have not been reported. This study aimed to analyze influenza prevalence among other respiratory infections and assess influenza vaccine efficacy in DM patients in Qatar. Statistical analysis was performed on data obtained from Hamad Medical Corporation (HMC) database for patients that visited the emergency department (ED) with respiratory-like illnesses. The analysis was done for the period between January 2016 to December 2018. Among 17,525 patients who visited HMC-ED with clinical symptoms of respiratory infections, 2611(14.9%) were reported to have DM. Among DM patients, influenza was the most prevalent respiratory pathogen at 48.9%. Influenza virus A (IVA) was the most circulating type, contributing to 38.4%, followed by IVB contributing to 10.4% of total respiratory infections. Among the typed IVA-positive cases, 33.4% were H1N1, and 7.7% were H3N2. A significant decrease in influenza infections was reported in vaccinated DM patients (14.5%) when compared to non-vaccinated patients (18.9%) (p-value = 0.006). However, there was no significant relaxation in the clinical symptoms among vaccinated DM patients compared to their non-vaccinated counterparts. In conclusion, influenza was the most common etiology for respiratory viral infection among diabetic patients at the leading healthcare provider in Qatar. Although vaccination reduced the incidence rate among DM patients, it was less effective in preventing symptoms. Further studies on a larger cohort and for a more extended period are required to investigate influenza prevalence and vaccine efficacy among DM patients.

Effectiveness of vaccination on influenza-related critical illnesses in the elderly population

OBJECTIVES

The prevention of serious influenza-related severe conditions due to influenza is important, particularly in elderly patients, age is a risk factor for death resulting from influenza-related respiratory diseases. The aim of the present study was to investigate the association of influenza vaccination with severe condition requiring critical care and death in elderly people, using vaccine records and healthcare administrative claims data in a Japanese city.

RESULTS

Among 5608 patients aged ≥65 years diagnosed with influenza, we identified 96 patients who had received invasive mechanical ventilation or died. Thereafter, we matched 384 controls with the cases. The cases were less vaccinated than the controls (37.5% vs. 56.0%, P < 0.01). In the multivariate analysis, influenza vaccination was associated with a lower proportion of the composite outcome (odds ratio, 0.35; 95% confidence interval, 0.21-0.60). In patients aged ≥80 years old and those with cardiovascular disease, influenza vaccination was associated with low composite outcomes.

CONCLUSIONS

Influenza vaccination was associated with reduced proportions of receiving invasive mechanical ventilation or influenza-related mortality, particularly in those aged ≥80 years old.

A study to evaluate the knowledge, vaccination status and acceptance of adult vaccinations against respiratory infections in patients with type 2 diabetes in South India

Introduction

Respiratory infections like influenza and pneumococcus increase mortality, morbidity, hospitalisation risks and healthcare costs in people with type 2 diabetes which can be prevented by vaccinations. However, there is not much data regarding how many people with type 2 diabetes in India receive pneumococcal and influenza vaccinations.

Methods

This is a cross-sectional study conducted between March 2022 to May 2022 at a tertiary care centre in South India. Patients were interviewed through face to face questionnaire regarding awareness, knowledge of influenza and pneumococcal infections, availability and need of vaccines, vaccination status and the possible reasons for not receiving vaccines.

Results

A total of 388 patients were recruited in the study. Knowledge about influenza and pneumococcal infections were present only in 4.8% and 4.1% respectively. And 98.7% of patients had no awareness about the availability and need for vaccines. Only 0.5% and 0.7% of patients received influenza and pneumococcal vaccinations respectively. After counselling and spreading awareness, 76.2% of patients said that they would receive vaccination in the next visit. Also, 23.19% of the patients refused to take any vaccinations even after counselling. And 23.7% of patients feared complications after vaccinations.

Conclusion

Pneumococcal and Influenza vaccination uptake rates are extremely low in people with type 2 diabetes in India. Urgent measures are required to increase the awareness in patients and healthcare workers about the availability, need for vaccinations and effectiveness of vaccines which would lead to improvement in vaccination rates.

Vaccination against Community-Acquired Pneumonia in Spanish Adults: Practical Recommendations by the NeumoExperts Prevention Group

In the adult population, community-acquired pneumonia (CAP) is a serious disease that is responsible for high morbidity and mortality rates, being frequently associated with multidrug resistant pathogens. The aim of this review is to update a practical immunization prevention guideline for CAP in Spain caused by prevalent respiratory pathogens, based on the available scientific evidence through extensive bibliographic review and expert opinion. The emergence of COVID-19 as an additional etiological cause of CAP, together with the rapid changes in the availability of vaccines and recommendations against SARS-CoV-2, justifies the need for an update. In addition, new conjugate vaccines of broader spectrum against pneumococcus, existing vaccines targeting influenza and pertussis or upcoming vaccines against respiratory syncytial virus (RSV) will be very useful prophylactic tools to diminish the burden of CAP and all of its derived complications. In this manuscript, we provide practical recommendations for adult vaccination against the pathogens mentioned above, including their contribution against antibiotic resistance. This guide is intended for the individual perspective of protection and not for vaccination policies, as we do not pretend to interfere with the official recommendations of any country. The use of vaccines is a realistic approach to fight these infections and ameliorate the impact of antimicrobial resistance. All of the recently available scientific evidence included in this review gives support to the indications established in this practical guide to reinforce the dissemination and implementation of these recommendations in routine clinical practice.

Does repeated influenza vaccination attenuate effectiveness? A systematic review and meta-analysis

BACKGROUND

Influenza vaccines require annual readministration; however, several reports have suggested that repeated vaccination might attenuate the vaccine's effectiveness. We aimed to estimate the reduction in vaccine effectiveness associated with repeated influenza vaccination.

METHODS

In this systematic review and meta-analysis, we searched MEDLINE, EMBASE, and CINAHL Complete databases for articles published from Jan 1, 2016, to June 13, 2022, and Web of Science for studies published from database inception to June 13, 2022. For studies published before Jan 1, 2016, we consulted published systematic reviews. Two reviewers (EJ-G and EJR) independently screened, extracted data using a data collection form, assessed studies' risk of bias using the Risk Of Bias In Non-Randomized Studies of Interventions (ROBINS-I) and evaluated the weight of evidence by Grading of Recommendations Assessment, Development, and Evaluation (GRADE). We included observational studies and randomised controlled trials that reported vaccine effectiveness against influenza A(H1N1)pdm09, influenza A(H3N2), or influenza B using four vaccination groups: current season; previous season; current and previous seasons; and neither season (reference). For each study, we calculated the absolute difference in vaccine effectiveness (ΔVE) for current season only and previous season only versus current and previous season vaccination to estimate attenuation associated with repeated vaccination. Pooled vaccine effectiveness and ∆VE were calculated by season, age group, and overall. This study is registered with PROSPERO, CRD42021260242.

FINDINGS

We identified 4979 publications, selected 681 for full review, and included 83 in the systematic review and 41 in meta-analyses. ΔVE for vaccination in both seasons compared with the current season was -9% (95% CI -16 to -1, I2=0%; low certainty) for influenza A(H1N1)pdm09, -18% (-26 to -11, I2=7%; low certainty) for influenza A(H3N2), and -7% (-14 to 0, I2=0%; low certainty) for influenza B, indicating lower protection with consecutive vaccination. However, for all types, A subtypes and B lineages, vaccination in both seasons afforded better protection than not being vaccinated.

INTERPRETATION

Our estimates suggest that, although vaccination in the previous year attenuates vaccine effectiveness, vaccination in two consecutive years provides better protection than does no vaccination. The estimated effects of vaccination in the previous year are concerning and warrant additional investigation, but are not consistent or severe enough to support an alternative vaccination regimen at this time.

FUNDING

WHO and the US National Institutes of Health.

Clinical impact of influenza vaccination after ST- and non-ST-segment elevation myocardial infarction - insights from the IAMI trial

BACKGROUND

Influenza vaccination early after myocardial infarction (MI) improves prognosis but vaccine effectiveness may differ dependent on type of MI.

METHODS

A total of 2,571 participants were prospectively enrolled in the Influenza vaccination after myocardial infarction (IAMI) trial and randomly assigned to receive in-hospital inactivated influenza vaccine or saline placebo. The trial was conducted at 30 centers in eight countries from October 1, 2016 to March 1, 2020. Here we report vaccine effectiveness in the 2,467 participants with ST-segment elevation MI (STEMI, n = 1,348) or non-ST-segment elevation MI (NSTEMI, n = 1,119). The primary endpoint was the composite of all-cause death, MI, or stent thrombosis at 12 months. Cumulative incidence of the primary and key secondary endpoints by randomized treatment and NSTEMI/STEMI was estimated using the Kaplan-Meier method. Treatment effects were evaluated with formal interaction testing to assess for effect modification.

RESULTS

Baseline risk was higher in participants with NSTEMI. In the NSTEMI group the primary endpoint occurred in 6.5% of participants assigned to influenza vaccine and 10.5% assigned to placebo (hazard ratio [HR], 0.60; 95% CI, 0.39-0.91), compared to 4.1% assigned to influenza vaccine and 4.5% assigned to placebo in the STEMI group (HR, 0.90; 95% CI, 0.54-1.50, P = .237 for interaction). Similar findings were seen for the key secondary endpoints of all-cause death and cardiovascular death. The Kaplan-Meier risk difference in all-cause death at one year was more pronounced in participants with NSTEMI (NSTEMI: HR, 0.47; 95% CI 0.28-0.80, STEMI: HR, 0.86; 95% CI, 0.43-1.70, interaction P = .028).

CONCLUSIONS

The beneficial effect of influenza vaccination on adverse cardiovascular events may be enhanced in patients with NSTEMI compared to those with STEMI.

Influenza vaccination trend and related factors among patients with diabetes in Korea: Analysis using a nationwide database

BACKGROUND

Subjects with diabetes are at higher risk of serious influenza-related complications. We aimed to investigate the yearly trend of influenza vaccination and factors associated with being unvaccinated for influenza in subjects with diabetes using a nationwide observational study performed within the recent decade.

METHODS

Among 105,732 subjects from the Korea National Health and Nutrition Examination Survey between 2007 and 2019, 8,632 with diabetes were included. We investigated the yearly trend of influenza vaccination and factors associated with being unvaccinated for influenza.

RESULTS

During the study period, the prevalence of influenza vaccination in subjects with diabetes showed a tendency to increase every year, reaching almost 60% in 2019, which was higher than the rate in subjects without diabetes. Younger age (adjusted hazard ratio (aHR) [95% CI] 11.29 [8.63-14.75] for < 50 years; 6.16 [5.21-7.29] for 50-65 years), male (aHR 1.67 [1.52-1.87]), current smoker (aHR 1.31 [1.00-1.72], lower-income status (aHR 1.46 [1.17, 1.84]), and high education level (aHR 1.30 [1.01-1.67]) were associated with being unvaccinated. Also, a poorer glycemic control with HbA1c ≥ 9% was found to be correlated with unvaccinated status (aHR 1.48 [1.15-1.90]).

CONCLUSION

The influenza vaccination rate is still unsatisfactory in subjects with diabetes. Young age, males, low-income level, high education level, and poor glycemic control were associated with unvaccinated status. Considering the risk-benefits of influenza vaccination in patients with diabetes, physicians should make an effort to increase vaccination rates, especially in low vaccination rate groups.

Chronic obstructive pulmonary disease and influenza vaccination effect in preventing outpatient and inpatient influenza cases

Evidence of influenza vaccine effectiveness in preventing confirmed influenza among persons diagnosed with chronic obstructive pulmonary disease (COPD) is scarce. We assessed the average effect of influenza vaccination in the current and prior seasons in preventing laboratory-confirmed influenza in COPD patients. We carried out a pooled test-negative case–control design in COPD patients hospitalized or presented to primary healthcare centres with influenza-like illness who were tested for influenza in 2015/2016 to 2019/2020 seasons in Navarre, Spain. Influenza vaccination status in the current and 5 prior seasons was compared between confirmed-influenza cases and test-negative controls. Vaccination effect was compared between target patients for vaccination with and without COPD. Out of 1761 COPD patients tested, 542 (31%) were confirmed for influenza and 1219 were test-negative controls. Average effect for current-season vaccination in preventing influenza was 40% (95% CI 20–54%), and for vaccination in prior seasons only was 24% (95% CI –10 to 47%). Point estimates seemed higher in preventing outpatient cases (60% and 58%, respectively) than inpatient cases (37% and 19%, respectively), but differences were no statistically significant. Influenza vaccination effect was similar in target population with and without COPD (p = 0.339). Influenza vaccination coverage in control patients with COPD was 68.3%. A 13.7% of the influenza cases in patients with COPD could be prevented by extending the influenza vaccine coverage. Average effect of current-season influenza vaccination was moderate to prevent influenza in COPD persons. The increase of influenza vaccination coverage can still prevent COPD exacerbations.

Low Levels of Influenza Vaccine Uptake among the Diabetic Population in Spain: A Time Trend Study from 2011 to 2020

(1) Background: In this work, we aim to describe influenza vaccine uptake among the diabetic population in Spain to assess the time trend from 2011 to 2020 and identify predictors of vaccine uptake among diabetes patients. (2) Methods: We conducted a descriptive cross-sectional study using the European Health Interview Survey for Spain (2014 and 2020) and the Spanish National Health Surveys (2011 and 2017). The independent variables analysed included socio-demographic characteristics, health-related variables and lifestyle variables. We matched each participant with diabetes with a non-diabetic participant based on age, sex, place of residence and year of survey. (3) Results: The overall coverage among diabetic adults was 52.1% compared to 40.6% for matched participants without diabetes (p < 0.01). The vaccine uptake among adults with diabetes was 52.6% in 2011, 54.38% in 2014 and 53.4% in 2017. The adjusted OR of having been vaccinated in 2020, with respect to 2011, was not significant at 0.87 (95% CI: 0.72–1.06). Factors such as being male, higher age, being affected by respiratory disease or cancer and being physically active were identified as positive predictors for influenza vaccination uptake, while smoking was a negative predictor. (4) Conclusions: The influenza vaccine uptake is below desirable levels among the adult diabetic population in Spain and has not improved from 2011 to 2020. More efforts should be made to increase influenza vaccine uptake in this high-risk group, especially for women, those aged 18–64 years, without other high-risk conditions and smokers.

Simple models to include influenza vaccination history when evaluating the effect of influenza vaccination

Background

Most reports of influenza vaccine effectiveness consider current-season vaccination only.

Aim

We evaluated a method to estimate the effect of influenza vaccinations (EIV) considering vaccination history.

Methods

We used a test-negative design with well-documented vaccination history to evaluate the average EIV over eight influenza seasons (2011/12–2018/19; n = 10,356). Modifying effect was considered as difference in effects of vaccination in current and previous seasons and current-season vaccination only. We also explored differences between current-season estimates excluding from the reference category people vaccinated in any of the five previous seasons and estimates without this exclusion or only for one or three previous seasons.

Results

The EIV was 50%, 45% and 38% in people vaccinated in the current season who had previously received none, one to two and three to five doses, respectively, and it was 30% and 43% for one to two and three to five prior doses only. Vaccination in at least three previous seasons reduced the effect of current-season vaccination by 12 percentage points overall, 31 among outpatients, 22 in 9–65 year-olds, and 23 against influenza B. Including people vaccinated in previous seasons only in the unvaccinated category underestimated EIV by 9 percentage points on average (31% vs 40%). Estimates considering vaccination of three or five previous seasons were similar.

Conclusions

Vaccine effectiveness studies should consider influenza vaccination in previous seasons, as it can retain effect and is often an effect modifier. Vaccination status in three categories (current season, previous seasons only, unvaccinated) reflects the whole EIV.

Effect of influenza vaccination in patients with asthma

BACKGROUND:

Although annual influenza vaccination is recommended for persons with asthma, its effectiveness in this patient population is not well described. We evaluated the effect of influenza vaccination in the current and previous seasons in preventing influenza among people with asthma.

METHODS:

Using population health data from the Navarre region of Spain for the 2015/16 to 2019/20 influenza seasons, we conducted a test-negative case–control study to assess the effect of influenza vaccination in the current and 5 previous seasons. From patients presenting to hospitals and primary health care centres with influenza-like illness who underwent testing for influenza, we estimated the effects of influenza vaccination among patients with asthma overall and between those presenting as inpatients or outpatients, as well as between patients with and without asthma.

RESULTS:

Of 1032 patients who had asthma and were tested, we confirmed that 421 had influenza and the remaining 611 were test-negative controls. We found that the average effect of influenza vaccination was 43% (adjusted odds ratio [OR] 0.57, 95% confidence interval [CI] 0.40 to 0.80) for current-season vaccination regardless of previous doses, and 38% (adjusted OR 0.62, 95% CI 0.39 to 0.96) for vaccination in previous seasons only. Effects were similar for outpatients and inpatients. Among patients with asthma and confirmed influenza, current-season vaccination did not reduce the odds of hospital admission (adjusted OR 1.05, 95% CI 0.51 to 2.18). Influenza vaccination effects were similar for patients with and without asthma.

INTERPRETATION:

We estimated that, on average, current or previous influenza vaccination of people with asthma prevented almost half of influenza cases. These results support recommendations that people with asthma receive influenza vaccination.