Influenza vaccination may have only minimum or no effect on COVID-19 in the aged population (original) (raw)

Effect of influenza vaccine on COVID-19 mortality: a retrospective study

Internal and Emergency Medicine

It has been proposed that vaccines may exert an unspecific protective effect against infectious agents, different than expected. Coronavirus disease 2019 (COVID-19) is a pandemic infection with high mortality in older patients due to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The high number of vaccinations may be one of the reasons why children show a lower susceptibility to SARS-CoV-2 infection and milder severity when compared to adults. We have designed a study aimed at investigating whether the influenza vaccine may reduce the susceptibility and severity of SARS-CoV-2 infection. We retrospectively enrolled 635 patients who accessed our Emergency Department from March 1st to June 30th, 2020, and were diagnosed with COVID-19 infection confirmed by an RT-PCR on an oropharyngeal swab. Clinical data, outcomes, and influenza vaccination status were collected from the electronic medical records of our Hospital. We also used data from the Italian Health Ministry to compare the prevalence of flu vaccination among the general population of the Lazio Region and our enrolled patients. We then compared clinical outcomes between vaccinated and non-vaccinated patients, by univariate and multivariate analysis. COVID-19-positive patients older than 65 years reported a lower prevalence of flu vaccination when compared to the general population residing in the Lazio (p = 0.004). After correction for gender, age, and comorbidities, we found a lower risk of death at 60 days in patients with flu vaccination than in not vaccinated patients (p = 0.001). Our study shows that flu vaccination could reduce the mortality of COVID-19. Prospective studies are needed to confirm this result.

Effectiveness of influenza vaccine in aging and older adults: comprehensive analysis of the evidence

Clinical Interventions in Aging, 2012

Foremost amongst the diseases preventable by vaccination is influenza. Worldwide, influenza virus infection is associated with serious adverse events leading to hospitalization, debilitating complications, and death in elderly individuals. Immunization is considered to be the cornerstone for preventing these adverse health outcomes, and vaccination programs are timed to optimize protection during the annual influenza season. Trivalent inactivated influenza virus vaccines are believed to be both effective and cost-saving; however, in spite of widespread influenza vaccination programs, rates of hospitalization for acute respiratory illness and cardiovascular diseases have been increasing in this population during recent annual influenza seasons. From meta-analyses summarizing estimates of influenza vaccine effectiveness from available observational clinical studies, this review aims to examine how effective current influenza vaccine strategies are in the aging and older adult population and to analyze which are the most important biases that interfere with measurements of influenza vaccine effectiveness. Furthermore, consideration is given to strategies that should be adopted in order to optimize influenza vaccine effectiveness in the face of immune exhaustion.

Influenza control in the 21st century: Optimizing protection of older adults

Vaccine, 2009

Older adults (≥65 years of age) are particularly vulnerable to influenza illness. This is due to a waning immune system that reduces their ability to respond to infection, which leads to more severe cases of disease. The majority (∼90%) of influenza-related deaths occur in older adults and, in addition, catastrophic disability resulting from influenza-related hospitalization represents a significant burden in this vulnerable population. Current influenza vaccines provide benefits for older adults against influenza; however, vaccine effectiveness is lower than in younger adults. In addition, antigenic drift is also a concern, as it can impact on vaccine effectiveness due to a mismatch between the vaccine virus strain and the circulating virus strain. As such, vaccines that offer higher and broader protection against both homologous and heterologous virus strains are desirable. Approaches currently available in some countries to meet this medical need in older adults may include the use of adjuvanted vaccines. Future strategies under evaluation include the use of high-dose vaccines; novel or enhanced adjuvantation of current vaccines; use of live attenuated vaccines in combination with current vaccines; DNA vaccines; recombinant vaccines; as well as the use of different modes of delivery and alternative antigens. However, to truly evaluate the benefits that these solutions offer, further efficacy and effectiveness studies, and better correlates of protection, including a precise measurement of the T cell responses that are markers for protection, are needed. While it is clear that vaccines with greater immunogenicity are required for older adults, and that adjuvanted vaccines may offer a short-term solution, further research is required to exploit the many other new technologies.

Clinical Effectiveness of Influenza Vaccination in Persons Younger Than 65 Years With High-Risk Medical Conditions

Archives of Internal Medicine, 2005

Background: Influenza vaccination has consistently been shown to prevent all-cause death and hospitalizations during influenza epidemics among seniors. However, such benefits have not yet been demonstrated among younger individuals with high-risk medical conditions. In the present study, we evaluated the effectiveness of influenza vaccine in persons recommended for vaccination of any age during an epidemic. Methods: We conducted a case-control study during the 1999-2000 influenza A epidemic nested in a cohort of 75227 primary care patients. End points were all-cause mortality and episodes of hospitalizations or general practitioner (GP) visits for influenza, pneumonia, other acute respiratory disease, acute otitis media, myocardial infarction, heart failure, and stroke. The effectiveness of vaccination was evaluated by means of logistic regression analysis with adjustments for age, sex, prior health care use, medication use, and comorbid conditions. Results: Among high-risk children and adolescents younger than 18 years (n=5933; 8% of the study population), 1 death, 3 hospitalizations for pneumonia, and 160 GP visits occurred. After adjustments, 43% (95% confidence interval [CI], 10%-64%) of visits were prevented. Among high-risk adults aged between 18 and 64 years (n=24928; 33% of the study population), 47 deaths, 23 hospitalizations, and 363 GP visits occurred. After adjustments, vaccination prevented 78% of deaths (95% CI, 39%-92%), 87% of hospitalizations (95% CI, 39%-97%), and 26% of GP visits (95% CI, 7%-47%). Among elderly persons (n = 44 366; 59% of the study population), 272 deaths and 166 hospitalizations occurred, and after adjustments the vaccine prevented these end points by 50% (95% CI, 23%-68%) and 48% (95% CI, 7%-71%), respectively. Conclusion: Persons with high-risk medical conditions of any age can substantially benefit from annual influenza vaccination during an epidemic.

Influenza Vaccination in Older Adults: Recent Innovations and Practical Applications

Drugs & Aging

Influenza can lead to serious illness, particularly for older adults. In addition to short-term morbidity and mortality during the acute infection, recovery can be prolonged and often incomplete. This may lead to persistent declines in health and function, including catastrophic disability, which has dramatic implications for the well-being and support needs of older adults and their caregivers. All of this means that prevention of infection and effective treatment when illness has occurred are of paramount importance. In this narrative review, we discuss the effectiveness of influenza vaccines for the prevention of influenza illness and serious outcomes in older adults. We review evidence of vaccine effectiveness for older adults in comparison with younger age groups, and also highlight the importance of frailty as a determinant of vaccine effectiveness. We then turn our attention to the question of why older and frailer individuals have poorer vaccine responses, and consider changes in immune function and inflammatory responses. This sets the stage for a discussion of newer influenza vaccine products that have been developed with the aim of enhancing vaccine effectiveness in older adults. We review the available evidence on vaccine efficacy, effectiveness and cost benefits, consider the potential place of these innovations in clinical geriatric practice, and discuss international advisory committee recommendations on influenza vaccination in older adults. Finally, we highlight the importance of influenza prevention to support healthy aging, along with the need to improve vaccine coverage rates using available vaccine products, and to spur development of better influenza vaccines for older adults in the near future.

Influenza-like Illness Incidence Is Not Reduced by Influenza Vaccination in a Cohort of Older Adults, Despite Effectively Reducing Laboratory-Confirmed Influenza Virus Infections

The Journal of infectious diseases, 2017

Data on the relative contribution of influenza virus and other respiratory pathogens to respiratory infections in community-dwelling older adults (≥60 years) are needed. A prospective observational cohort study was performed in the Netherlands during 2 winters. Nasopharyngeal and oropharyngeal swabs were collected during influenza-like illness (ILI) episodes and from controls. Viruses and bacteria were identified by multiplex ligation-dependent probe amplification assay and conventional bacterial culture. The ILI incidence in the consecutive seasons was 7.2% and 11.6%, and influenza virus caused 18.9% and 34.2% of ILI episodes. Potential pathogen were detected in 80% of the ILI events with influenza virus, coronaviruses, rhinoviruses, human metapneumovirus, respiratory syncytial virus, parainfluenza viruses, and Haemophilus influenzae being the most common. Influenza vaccination reduced influenza virus infection by 73% (95% confidence interval [CI], 26%-90%) and 51% (95% CI, 7%-74%)...

Cochrane re-arranged: Support for policies to vaccinate elderly people against influenza

Vaccine, 2013

The 2010 Cochrane review on efficacy, effectiveness and safety of influenza vaccination in the elderly by Jefferson et al. covering dozens of clinical studies over a period of four decades, confirmed vaccine safety, but found no convincing evidence for vaccine effectiveness (VE) against disease thus challenging the ongoing efforts to vaccinate the elderly.

Association between Exposure to Influenza Vaccination and COVID-19 Diagnosis and Outcomes

Vaccines, 2020

We explored whether influenza vaccination (IV) affects susceptibility to SARS-CoV-2 infection and clinical outcomes in COVID-19 patients in 17,608 residents of the Italian province of Reggio Emilia undergoing a SARS-CoV-2 test. Exposure to IV was ascertained and the strength of the association with SARS-CoV-2 positivity expressed with odds ratios (OR). Rates of hospitalisations and death in those found positive were assessed and hazard ratios (HR) were estimated. The prevalence of IV was 34.3% in the 4885 SARS-CoV-2 positive and 29.5% in the 12,723 negative subjects, but the adjusted OR indicated that vaccinated individuals had a lower probability of testing positive (OR = 0.89; 95% CI 0.80-0.99). Among the 4885 positive individuals, 1676 had received IV. After adjusting for confounding factors, there was no association between IV and hospitalisation (1.00; 95% CI 0.84-1.29) or death (HR = 1.14; 95% CI 0.95-1.37). However, for patients age ≥65 vaccinated close to the SARS-CoV-2 outbreak, HRs were 0.66 (95% CI: 0.44-0.98) and 0.70 (95% CI 0.50-1.00), for hospitalisation and death, respectively. In this study, IV was associated with a lower probability of COVID-19 diagnosis. In COVID-19 patients, overall, IV did not affect outcomes, although a protective effect was observed for the elderly receiving IV almost in parallel with the SARS-CoV-2 outbreak. These findings provide reassurance in planning IV campaigns and underscore the need for exploring further their impact on COVID-19.

Influenza Vaccine Prevents Medically Attended Influenza-Associated Acute Respiratory Illness in Adults Aged ≥50 Years

The Journal of infectious diseases, 2014

There are few estimates of effectiveness influenza vaccine in preventing serious outcomes due to influenza in older adults. Adults aged ≥50 years who sought medical care for acute respiratory illness were enrolled. A nose/throat swab was tested for influenza virus by reverse transcription-polymerase chain reaction. Clinical and demographic data were collected, including verification of receipt of trivalent inactivated influenza vaccination (IIV-3). Adjusted odds ratios were estimated by multivariable logistic regression models with an L1 penalty on all covariates except vaccination status. A total of 1047 subjects were enrolled from November through April during 5 influenza seasons during 2006-2012, excluding the 2009-2010 season. Of those enrolled, 927 (88%) had complete influenza virus testing, vaccination status, and demographic data obtained. Of 86 (9.3%) influenza virus-positive patients, 47 (55%) were vaccinated. Of 841 influenza virus-negative patients, 646 (76.8%) were va...