Inactivated influenza vaccines for prevention of community-acquired pneumonia: the limits of using nonspecific outcomes in vaccine effectiveness studies

Mapping and ranking outcomes for the evaluation of seasonal influenza vaccine efficacy and effectiveness: a delphi study

BACKGROUND

Protection provided by seasonal influenza vaccination (SIV) may be measured against numerous outcomes, and their heterogeneity may hamper decision-making. The aim of this study was to explore outcomes used for estimation of SIV efficacy/effectiveness (VE) and obtain expert consensus on their importance.

RESEARCH DESIGN AND METHODS

An umbrella review was first conducted to collect and map outcomes considered in systematic reviews of SIV VE. A Delphi study was then performed to reach expert convergence on the importance of single outcomes, measured on a 9-point Likert scale, in principal target groups, namely children, working-age adults, older adults, subjects with co-morbidities and pregnant women.

RESULTS

The literature review identified 489 outcomes. Following data reduction, 20 outcomes were selected for the Delphi process. After two Delphi rounds and a final consensus meeting, convergence was reached. All 20 outcomes were judged to be important or critically important. More severe outcomes, such as influenza-related hospital encounters and mortality with or without laboratory confirmation, were generally top-ranked across all target groups (median scores ≥8 out of 9).

CONCLUSIONS

Rather than focusing on laboratory-confirmed infection per se, experimental and observational VE studies should include more severe influenza-related outcomes because they are expected to exercise a greater impact on decision-making.

Incidence and disease burden of community-acquired pneumonia in southeastern China: data from integrated medical resources

Community-acquired pneumonia (CAP) is a lower respiratory tract infection. It is one of the commonest infectious diseases and the third leading cause of death worldwide. However, the epidemiological profiles of CAP in southeastern China are unknown. Data of inpatients and outpatients diagnosed with CAP from January 1, 2015 to December 31, 2020 were obtained from the National Healthcare Big Data in Fuzhou (Fuzhou Database). This database covers medical data from 37 hospitals and 159 community health service stations. The incidence rate, treatment pattern, and direct medical costs of CAP were assessed using clinical data. A total of 8,156,237 patients were enrolled, with a mean age of 33.72 ± 20.88 years. The overall incidence rate of CAP was 3.13 (95% confidence interval [CI]: 3.11-3.15) per 1000 person-years (PY), with 15.97 (95% CI: 15.85-16.08) per 1000 PY in children below 5 years old and 2.62 (95% CI: 2.57-2.66) per 1000 PY in the elderly ≥60 years. The cost per outpatient was $242.83 ± 341.62, and the cost per inpatient was $4,530.4 ± 9,151.68. The three most used therapeutic drugs in patients with CAP are cefotaxime, moxifloxacin, and azithromycin. In addition, despite the ability of both imported and domestic pneumococcal conjugate vaccines to reduce the incidence rate of CAP, the current vaccination coverage rates were relatively low. We suggest that more attention should be paid to the disease burden of CAP, especially due to its great economic burden in China.

Vaccine Effectiveness Against Influenza-Associated Lower Respiratory Tract Infections in Hospitalized Adults, Louisville, Kentucky, 2010-2013

Background

Preventing severe complications of influenza such as hospitalization is a public health priority; however, estimates of influenza vaccine effectiveness (VE) against influenza-associated acute lower respiratory tract infection (LRTI) hospitalizations are limited. We examined influenza VE against influenza-associated LRTIs in hospitalized adult patients.

Methods

We retrospectively analyzed data from a randomized trial of oseltamivir treatment in adults hospitalized with LRTI in Louisville, Kentucky, from 2010 to 2013. Patients were systematically tested for influenza at the time of enrollment. We estimated VE as 1 - the adjusted odds ratio (aOR) of antecedent vaccination in influenza-positives vs negatives × 100%. Vaccination status was obtained by patient self-report. Using logistic regression adjusting for age, sex, season, timing of illness, history of chronic lung disease, and activities of daily living, we estimated VE against hospitalized influenza-associated LRTIs and community-acquired pneumonia (CAP) with radiographic findings of infiltrate.

Results

Of 810 patients with LRTI (median age, 62 years), 184 (23%) were influenza-positive and 57% had radiographically confirmed CAP. Among influenza-positives and -negatives, respectively, 61% and 69% were vaccinated. Overall, 29% were hospitalized in the prior 90 days and >80% had comorbidities. Influenza-negatives were more likely to have a history of chronic obstructive pulmonary disease than influenza-positives (59% vs 48%; P = .01), but baseline medical conditions were otherwise similar. Overall, VE was 35% (95% CI, 4% to 56%) against influenza-associated LRTI and 51% (95% CI, 13% to 72%) against influenza-associated radiographically confirmed CAP.

Conclusions

Vaccination reduced the risk of hospitalization for influenza-associated LRTI and radiographically confirmed CAP. Clinicians should maintain high rates of influenza vaccination to prevent severe influenza-associated complications.

Influenza vaccination and prevention of antimicrobial resistance

INTRODUCTION

Abuse and misuse of available antimicrobial drugs have increased antimicrobial resistance (AMR), with relevant adverse health and economic impacts. Several factors suggest that the influenza vaccine is a possible effective measure to control AMR through a significant reduction in antibiotic consumption. In this paper, aspects related will be discussed.

AREAS COVERED

Although the effectiveness of influenza immunization can significantly vary according to the study design, the circulating influenza viruses, the type of vaccine, the age of the enrolled subjects, the outcome measured and the season of the study, all experts agree that the influenza vaccine can significantly reduce the risk of contracting influenza in subjects of any age. Consequently, influenza vaccination may reduce the number of bacterial superimposed infections that can complicate influenza and require antibiotic prescriptions

EXPERT COMMENTARY

Several indirect and direct observations seem to indicate that influenza vaccines can play an important role in reducing influenza-related antibiotic prescriptions. This finding can lead to at least two undeniable advantages, reductions in drug expenditure and limitations of the risk of favoring AMR development. However, only when universal vaccination is accepted and implemented will the true advantages of the influenza vaccine in reducing AMR development be completely known and exploited.

Effectiveness of inactivated influenza vaccine against laboratory-confirmed influenza pneumonia among adults aged ≥65 years in Japan

BACKGROUND

The effectiveness of inactivated influenza vaccine (IIV) against laboratory-confirmed influenza pneumonia in older adults remains to be established.

METHODS

Pneumonia patients aged ≥65 years who visited a study hospital in Chiba, Japan, were prospectively enrolled from February 2012 to January 2014. Sputum samples were collected from participants and tested for influenza virus by polymerase chain reaction assays. Influenza vaccine effectiveness (IVE) against laboratory-confirmed influenza pneumonia was estimated by a test-negative design.

RESULTS

Among a total of 814 pneumonia patients, 42 (5.2%) tested positive for influenza: 40 were positive for influenza A virus, and two were positive for influenza B virus. The IVE against laboratory-confirmed influenza pneumonia was 58.3% (95% confidence interval, 28.8-75.6%). The IVE against influenza pneumonia hospital admission, severe pneumonia, and death was 60.2% (95% CI, 22.8-79.4%), 65.5% (95% CI, 44.3-78.7%), and 71% (95% CI, -62.9% to 94.8%), respectively. In the subgroup analyses, the IVE against influenza pneumonia was higher for patients with immunosuppressive conditions (85.9%; 95% CI, 67.4-93.9%) than for those without (48.7%; 95% CI, 2.7-73%) but did not differ by patients' statin use status.

CONCLUSION

IIV effectively reduces the risk of laboratory-confirmed influenza pneumonia in older adults.

Risk factors for community-acquired pneumonia among adults in Kenya: a case-control study

BACKGROUND

Pneumonia is a leading cause of morbidity and mortality among adults worldwide; however, the risk factors for community-acquired pneumonia in Africa are not well characterized.

METHODS

The authors recruited 281 cases of community-acquired pneumonia and 1202 hospital controls among patients aged ≥15 years who attended Kilifi District Hospital/Coast Provincial General Hospital in Kenya between 1994 and 6. Cases were admissions with an acute illness with ≥2 respiratory signs and evidence of consolidation on a chest radiograph. Controls were patients without signs of pneumonia, frequency matched by age, sex and hospital. Risk factors related to socio-demographic factors, drug use, clinical history, contact patterns and exposures to indoor air pollution were investigated by questionnaire, anthropometric measurements and laboratory assays. Associations were evaluated using a hierarchical logistic regression model.

RESULTS

Pneumonia was associated with human immunodeficiency virus (HIV) infection (Odds Ratio [OR] 2.06, 95% CI 1.44-3.08), anemia (OR 1.91, 1.31-2.74), splenomegaly (OR 2.04, 95% CI 1.14-3.41), recent history of pneumonia (OR 4.65, 95% CI 1.66-12.5), history of pneumonia >2 years previously (OR 17.13, 95% CI 5.01-60.26), coryza in the 2 weeks preceding hospitalization (OR 2.09, 95% CI 1.44-3.03), current smoking (2.19, 95% CI 1.39-3.70), use of khat (OR 3.44, 95% CI 1.72-7.15), use of snuff (OR 2.67, 95% CI 1.35-5.49) and contact with several animal species. Presence of a Bacillus Calmette-Guerin (BCG) scar was associated with protection (OR 0.51, 95% CI 0.32-0.82). The risk factors varied significantly by sex.

CONCLUSION

Pneumonia in Kenyan adults was associated with global risk factors, such as HIV and smoking, but also with specific local factors like drug use and contact with animals. Intervention strategies should account for sex-specific differences in risk factors.

Diagnosis and treatment of community-acquired pneumonia in adults: 2016 clinical practice guidelines by the Chinese Thoracic Society, Chinese Medical Association

Community‐acquired pneumonia (CAP) in adults is an infectious disease with high morbidity in China and the rest of the world. With the changing pattern in the etiological profile of CAP and advances in medical techniques in diagnosis and treatment over time, Chinese Thoracic Society of Chinese Medical Association updated its CAP guideline in 2016 to address the standard management of CAP in Chinese adults. Extensive and comprehensive literature search was made to collect the data and evidence for experts to review and evaluate the level of evidence. Corresponding recommendations are provided appropriately based on the level of evidence. This updated guideline covers comprehensive topics on CAP, including aetiology, antimicrobial resistance profile, diagnosis, empirical and targeted treatments, adjunctive and supportive therapies, as well as prophylaxis. The recommendations may help clinicians manage CAP patients more effectively and efficiently. CAP in pediatric patients and immunocompromised adults is beyond the scope of this guideline. This guideline is only applicable for the immunocompetent CAP patients aged 18 years and older. The recommendations on selection of antimicrobial agents and the dosing regimens are not mandatory. The clinicians are recommended to prescribe and adjust antimicrobial therapies primarily based on their local etiological profile and results of susceptibility testing, with reference to this guideline.

Hospitalized Patients with Acute Pneumonia

Pneumonia is one of the leading causes of mortality and hospitalization among US adults. The decision to admit patients from the emergency department is a major one because of its impact on patients and the hospital. The diagnosis of pneumonia is often clinical and based on symptoms and signs combined with radiographic findings. There are multiple severity assessments available that can guide treatment, prognosis, and disposition. Viruses are an important cause of pneumonia and require early recognition and treatment. The recommended treatment for community-acquired pneumonia includes a beta lactam plus a macrolide or a respiratory fluoroquinolone.

Incidence of Pneumococcal Pneumonia Among Adults in Rural Thailand, 2006-2011: Implications for Pneumococcal Vaccine Considerations

The incidence of pneumococcal pneumonia among adults is a key driver for the cost-effectiveness of pneumococcal conjugate vaccine used among children. We sought to obtain more accurate incidence estimates among adults by including results of pneumococcal urine antigen testing (UAT) from population-based pneumonia surveillance in two Thai provinces. Active surveillance from 2006 to 2011 identified acute lower respiratory infection (ALRI)-related hospital admissions. Adult cases of pneumococcal pneumonia were defined as hospitalized ALRI patients aged ≥ 18 years with isolation of Streptococcus pneumoniae from blood or with positive UAT. Among 39,525 adult ALRI patients, we identified 481 pneumococcal pneumonia cases (105 by blood culture, 376 by UAT only). Estimated incidence of pneumococcal pneumonia hospitalizations was 30.5 cases per 100,000 persons per year (2.2 and 28.3 cases per 100,000 persons per year by blood culture and UAT, respectively). Incidence varied between 22.7 in 2007 and 43.5 in 2010, and increased with age to over 150 per 100,000 persons per year among persons aged ≥ 70 years. Viral coinfections including influenza A/B, respiratory syncytial virus (RSV), and adenovirus occurred in 11% (44/409) of pneumococcal pneumonia cases tested. Use of UAT to identify cases of pneumococcal pneumonia among adults in rural Thailand substantially increases estimates of pneumococcal pneumonia burden, thereby informing cost-effectiveness analyses and vaccine policy decisions.

Association Between Hospitalization With Community-Acquired Laboratory-Confirmed Influenza Pneumonia and Prior Receipt of Influenza Vaccination

IMPORTANCE

Few studies have evaluated the relationship between influenza vaccination and pneumonia, a serious complication of influenza infection.

OBJECTIVE

To assess the association between influenza vaccination status and hospitalization for community-acquired laboratory-confirmed influenza pneumonia.

DESIGN, SETTING, AND PARTICIPANTS

The Etiology of Pneumonia in the Community (EPIC) study was a prospective observational multicenter study of hospitalizations for community-acquired pneumonia conducted from January 2010 through June 2012 at 4 US sites. In this case-control study, we used EPIC data from patients 6 months or older with laboratory-confirmed influenza infection and verified vaccination status during the influenza seasons and excluded patients with recent hospitalization, from chronic care residential facilities, and with severe immunosuppression. Logistic regression was used to calculate odds ratios, comparing the odds of vaccination between influenza-positive (case) and influenza-negative (control) patients with pneumonia, controlling for demographics, comorbidities, season, study site, and timing of disease onset. Vaccine effectiveness was estimated as (1 - adjusted odds ratio) × 100%.

EXPOSURE

Influenza vaccination, verified through record review.

MAIN OUTCOMES AND MEASURES

Influenza pneumonia, confirmed by real-time reverse-transcription polymerase chain reaction performed on nasal/oropharyngeal swabs.

RESULTS

Overall, 2767 patients hospitalized for pneumonia were eligible for the study; 162 (5.9%) had laboratory-confirmed influenza. Twenty-eight of 162 cases (17%) with influenza-associated pneumonia and 766 of 2605 controls (29%) with influenza-negative pneumonia had been vaccinated. The adjusted odds ratio of prior influenza vaccination between cases and controls was 0.43 (95% CI, 0.28-0.68; estimated vaccine effectiveness, 56.7%; 95% CI, 31.9%-72.5%).

CONCLUSIONS AND RELEVANCE

Among children and adults hospitalized with community-acquired pneumonia, those with laboratory-confirmed influenza-associated pneumonia, compared with those with pneumonia not associated with influenza, had lower odds of having received influenza vaccination.

Vaccination in the elderly: what can be recommended?

The age-associated increased susceptibility to infectious disease would suggest that vaccination should be a route to promote healthy aging and keep our seniors autonomous and independent. While vaccination represents a cost-effective and efficient strategy at community level, the ability of the immune system to mount a protective immune response is still unpredictable at the level of the individual. Thus, at a similar age, some individuals, including the elderly, might still be 'good' responders while some other, even younger, would definitely fail to mount a protective response. In this review, the current burden of vaccine-preventable diseases in the aging and aged population will be detailed with the aim to identify the ideal vaccine candidates over the age of 50 years. This article will conclude with potential strategies to reduce, as best as possible, this burden and the imperative need to overcome barriers in extending current vaccine coverage towards to a lifelong vaccine schedule.

The impact of vaccination on influenza-related respiratory failure and mortality in hospitalized elderly patients over the 2013-2014 season

BACKGROUND

Seasonal Influenza ("the flu") is a respiratory illness caused by influenza viruses. Yearly influenza vaccination is considered to be protective against illness and/or severity of illness and is recommended by CDC for all individuals > 6 months of age. However, the effectiveness of influenza vaccine in older individuals has come under question.

OBJECTIVES

To describe the clinical characteristics and treatment outcomes of patients admitted to an academic tertiary care Veterans Administration hospital with influenza during the 2013-2014 influenza season and determine the impact, if any, of prior influenza vaccination upon patient outcomes.

METHODS

Medical electronic records were searched for all patients admitted to the Little Rock Veterans Administration Hospital with proven influenza during the 2013-2014 influenza season. Cohorts of vaccinated and non-vaccinated patients were then compared to determine the impact of prior influenza vaccination upon respiratory-failure and mortality.

RESULTS

Seventy patients met selection criteria. Mean age was 66 years. Sixty-four (91%) patients had at least one underlying co-morbid condition; these conditions included COPD, congestive heart failure, diabetes, and cancer. 60/70 (85%) tested positive for Influenza A, and 43 tested positive for H1N1. Oseltamivir was initiated in 55 (78%) patients. Forty-four percent of the patients had been vaccinated. When separated by vaccination status, those who had been vaccinated had higher rates of ICU admission, need for mechanical or non-invasive ventilation, and mortality. All but mortality reached statistical significance.

CONCLUSION

The data suggest that there was no protective effect from prior vaccination in preventing hospital admission, respiratory failure, and mortality in this population of older men admitted to the hospital with influenza.

Cost-effectiveness of influenza vaccination in prior pneumonia patients in Israel

Pneumonia is a common complication of influenza infection, and accounts for the majority of influenza mortality. Both the WHO and the Ministry of Health in Israel prioritize seasonal influenza vaccination primarily on the basis of age and specific co-morbidities. Here we consider whether the targeting of individuals previously infected with pneumonia for influenza vaccination would be a cost-effective addition to the current policy. We performed a retrospective cohort data analysis of 163,990 cases of pneumonia hospitalizations and 1,305,223 cases of outpatient pneumonia from 2004 to 2012, capturing more than 54% of the Israeli population. Our findings demonstrate that patients infected with pneumonia in the year prior had a substantially higher risk of becoming infected with pneumonia in subsequent years (relative risk >2.34, p<0.01). Results indicated that the benefit of targeting for influenza vaccination patients hospitalized with pneumonia in prior year would be cost-saving regardless of age. Complementing the current policy with the targeting of prior pneumonia patients would require vaccination of only a further 2.3% of the Israeli population to save additional 204-407 quality-adjusted life years (QALYs) annually at a mean price of 58-1056 USD/QALY saved. Global uncertainty analysis demonstrates that the cost-effectiveness of adding this policy is robust over a vast range of conditions. As prior pneumonia patients are currently not prioritized for influenza vaccination in Israel, nor elsewhere, this study suggests a novel supplement of current policies to improve cost-effectiveness of influenza vaccination. Future studies should use case-control study to further evaluate the effectiveness of vaccination in prior pneumonia patients.

Use of vaccines as probes to define disease burden

Vaccine probe studies have emerged in the past 15 years as a useful way to characterise disease. By contrast, traditional studies of vaccines focus on defining the vaccine effectiveness or efficacy. The underlying basis for the vaccine probe approach is that the difference in disease burden between vaccinated and unvaccinated individuals can be ascribed to the vaccine-specific pathogen. Vaccine probe studies can increase understanding of a vaccine's public health value. For instance, even when a vaccine has a seemingly low efficacy, a high baseline disease incidence can lead to a large vaccine-preventable disease burden and thus that population-based vaccine introduction would be justified. So far, vaccines have been used as probes to characterise disease syndromes caused by Haemophilus influenzae type b, pneumococcus, rotavirus, and early infant influenza. However, vaccine probe studies have enormous potential and could be used more widely in epidemiology, for example, to define the vaccine-preventable burden of malaria, typhoid, paediatric influenza, and dengue, and to identify causal interactions between different pathogens.

Effectiveness of inactivated influenza vaccines in preventing influenza-associated deaths and hospitalizations among Ontario residents aged ≥ 65 years: estimates with generalized linear models accounting for healthy vaccinee effects

BACKGROUND

Estimates of the effectiveness of influenza vaccines in older adults may be biased because of difficulties identifying and adjusting for confounders of the vaccine-outcome association. We estimated vaccine effectiveness for prevention of serious influenza complications among older persons by using methods to account for underlying differences in risk for these complications.

METHODS

We conducted a retrospective cohort study among Ontario residents aged ≥ 65 years from September 1993 through September 2008. We linked weekly vaccination, hospitalization, and death records for 1.4 million community-dwelling persons aged ≥ 65 years. Vaccine effectiveness was estimated by comparing ratios of outcome rates during weeks of high versus low influenza activity (defined by viral surveillance data) among vaccinated and unvaccinated subjects by using log-linear regression models that accounted for temperature and time trends with natural spline functions. Effectiveness was estimated for three influenza-associated outcomes: all-cause deaths, deaths occurring within 30 days of pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations.

RESULTS

During weeks when 5% of respiratory specimens tested positive for influenza A, vaccine effectiveness among persons aged ≥ 65 years was 22% (95% confidence interval [CI], -6%-42%) for all influenza-associated deaths, 25% (95% CI, 13%-37%) for deaths occurring within 30 days after an influenza-associated pneumonia/influenza hospitalization, and 19% (95% CI, 4%-31%) for influenza-associated pneumonia/influenza hospitalizations. Because small proportions of deaths, deaths after pneumonia/influenza hospitalizations, and pneumonia/influenza hospitalizations were associated with influenza virus circulation, we estimated that vaccination prevented 1.6%, 4.8%, and 4.1% of these outcomes, respectively.

CONCLUSIONS

By using confounding-reducing techniques with 15 years of provincial-level data including vaccination and health outcomes, we estimated that influenza vaccination prevented ~4% of influenza-associated hospitalizations and deaths occurring after hospitalizations among older adults in Ontario.