The flu vaccine and seniors — what do doctors who are critical of vaccination say?

Aim of the study: High-dose trivalent, inactivated, split-virus influenza vaccine (IIV3-HD) has been available in the US since 2009 for adults aged ≥ 65 years. To better understand how IIV3-HD provides improved protection against influenza, we systematically reviewed clinical studies comparing immune responses to IIV3-HD and standard-dose trivalent vaccine (IIV3-SD).

Aim of the study: In the elderly, traditional influenza inactivated vaccines are often only modestly immunogenic, owing to immunosenescence. Given that adjuvantation is a means of enhancing the immune response, the trivalent inactivated vaccine adjuvanted with MF59 (MF59-TIV) was specifically designed to overcome this problem.

Results: Of the 1993 papers screened, 11 (6 case-control, 3 cohort and 2 prospective case-control) studies were identified. Hospitalization due to pneumonia/influenza and laboratory-confirmed influenza were reported in more than one study, while other outcomes (influenza-like illness, cardio- and cerebrovascular accidents) were investigated only by one study each. Pooled analysis of four case-control studies showed an adjusted MF59-TIV effectiveness of 51% (95% CI: 39-61%) against hospitalizations for pneumonia/influenza among community-dwelling seniors. Pooled results of the adjusted vaccine effectiveness against laboratory-confirmed influenza were also high (60.1%), although the 95% CI passed through zero (-1.3 to 84.3%). Other single community-based studies showed very high effectiveness of MF59-TIV in preventing hospitalizations for acute coronary [87% (95% CI: 35-97%)] and cerebrovascular [93% (95% CI: 52-99%)] events.

Aim of the study: In order to support policymakers in allocating resources, we aimed to assess vaccine effectiveness (VE) of inactivated influenza vaccines (IIVs) available for Italian adults in the 2023/2024 season.

Results: Of 1,664 adults analyzed, most (82%) of which were ≥65 years, 114 (6.9%) tested positive for influenza A. Most (92%) cases were caused by subclades 6B.1A.5a.2a and 6B.1A.5a.2a.1 of the A(H1N1)pdm09 subtype. In older adults aged ≥65 years vaccination was effective at 51% (95% CI: 8%, 74%) against any influenza A and 49% (95% CI: 2%, 73%) against A(H1N1)pdm09. Compared with non-vaccinated older adults, VE point estimates for the adjuvanted and, especially, high-dose IIVs were higher than those for the standard-dose non-adjuvanted IIV. The 2023/2024 seasonal influenza vaccination proved moderately effective in preventing hospitalization for laboratory-confirmed influenza. Being more appropriate for older adults, local policymakers and vaccinating physicians should maximize adoption of the enhanced IIVs.

Aim of the study: Fluzone® High-Dose (IIV3-HD) is a trivalent, inactivated, split-virus influenza vaccine indicated for use in older adults (≥65 years of age). It contains 60 µg hemagglutinin of each influenza strain, which is four times the hemagglutinin content of standard-dose influenza vaccines, including Fluzone (IIV3-SD).

Results: We also discuss the potential application of IIV3-HD in adults 50-64 years of age and in individuals who may respond poorly to standard-dose influenza vaccines. Expert commentary: Multiple studies conducted since 2004 have consistently shown that, in older adults, IIV3-HD induces substantially greater antibody responses and better protection against influenza and influenza-associated hospitalization than IIV3-SD. Health economic analyses suggest that IIV3-HD can be a cost-effective alternative to standard-dose trivalent or quadrivalent inactivated influenza vaccines and can even be cost-saving compared to IIV3-SD in older adults. Further investigation of IIV3-HD vaccination as a way to improve immune responses and protection against influenza in immunocompromised individuals is warranted.

Aim of the study: Adults aged 65 years or older suffer the most severe health effects of seasonal flu. Although the influenza vaccine is effective in preventing influenza virus infection and its complications, it is not as effective in the elderly due to age-associated immunosenescence phenomenon.

Results: Although the influenza vaccine is effective in preventing influenza virus infection and its complications, it is not as effective in the elderly due to age-associated immunosenescence phenomenon. Since 2009, a high-dose trivalent influenza vaccine has been approved in the United States for the immunization of people ≥ 65 years with an antigen concentration four times higher than the standard vaccine. Multiple clinical trials carried out over different seasons, and using different methodologies, have shown that the high-dose trivalent influenza vaccine is not only more effective, but it also has a similar safety profile and is more immunogenic than the standard dose vaccine in the prevention of flu and its complications in the elderly.

Aim of the study: Seasonal influenza is a major public health problem, particularly in older people. Influenza vaccine is the most effective way to prevent influenza virus infection and its complications, but due to immunosenescence, older people do not respond efficiently to immunization.

Results: Influenza vaccine is the most effective way to prevent influenza virus infection and its complications, but due to immunosenescence, older people do not respond efficiently to immunization. In 2009, a high-dose trivalent influenza vaccine (IIV3-HD), containing four times more antigen than the standard-dose vaccine, was approved in the United States for the immunization of people aged 65 years and over. Numerous clinical trials, carried out at different seasons and using different methodologies, have shown that the IIV3-HD vaccine is, as well as safe, more immunogenic and more effective than the standard-dose vaccine in preventing influenza virus infection and its complications in older people. This paper reviews the available evidence on the efficacy and effectiveness of the IIV3-HD influenza vaccine in the elderly, with information from randomized clinical trials, as well as observational studies of real-world clinical practice and in systematic reviews/meta-analyses.

Aim of the study: Although some controversy exists about the necessity of the annual influenza vaccine in the elderly population, it has been established that the benefits outweigh the risks. Vaccinating elderly patients helps prevent influenza-related mortality, avoids debilitating complications, and even averts exacerbation of certain comorbidities including chronic obstructive pulmonary disease, asthma, and metabolic disorders such as diabetes.

Results: Even with all of its established benefits, barriers to access can prevent elderly individuals from receiving the vaccine. These barriers include a lack of education regarding the vaccine and a lack of vaccination enforcement by health care providers. As health care providers, it is our responsibility not only to treat disease, but also to prevent disease from occurring. The influenza vaccine is an easy and cost-effective way to prevent infection from the virus and the serious complications that may accompany it which, in turn, helps improve patients' quality of life.

Aim of the study: The aim of this systematic review is to evaluate whether common adult vaccinations are associated with a reduced risk of dementia.

Results: Twenty-one studies (n = 104 031 186 participants) were included. Vaccination against herpes zoster was associated with a reduced risk of any dementia (RR 0.76, 95% CI 0.69-0.83) and Alzheimer's disease (RR 0.53, 95% CI 0.44-0.64). Influenza vaccination was linked to a reduction in dementia risk (RR 0.87, 95% CI 0.77-0.99), as was pneumococcal vaccination (RR 0.64, 95% CI 0.47-0.87) for Alzheimer's disease. Tetanus, diphtheria, pertussis (Tdap) vaccination was also associated with a significant reduction for any dementia (RR 0.67, 95% CI 0.54-0.83). Adult vaccinations, particularly against herpes zoster, influenza, pneumococcus and Tdap, are associated with a lower risk of dementia. Vaccination strategies should be incorporated into public health initiatives for dementia prevention.

Aim of the study: The 2024-2025 influenza season in Taiwan was notably more severe than the prior season, with severe cases increasing from 1433 to 2215 and deaths increasing from 297 to 545. Vaccination coverage among adults aged ≥65 years also declined from 53.6% to 48.1%. All government-funded vaccines in the 2024-2025 season were inactivated standard-dose trivalent influenza vaccines.

Results: Despite a decline in vaccination coverage, the vaccine demonstrated robust protection against severe outcomes. The adjusted VE was 71.9% (95% CI: [63.0-78.8]) against 30-day mortality and 70.0% (95% CI: [62.1-76.2]) against ICU admissions. Protection against influenza-associated hospitalizations was 58.2% (95% CI: [52.9-62.9]), while VE against outpatient visits was 44.8% (95% CI: [42.4-47.1]). Propensity score matching showed similar trend but generally lower VE estimates. Our findings confirm that the influenza vaccine remains highly effective in preventing severe outcomes, despite the reduced population uptake and increased disease burden. The methodology, consistent with our prior season's analysis, underscores the reliability of these results. We conclude that enhancing vaccination coverage among the elderly is critical to mitigating the impact of severe seasonal epidemics.