A groundbreaking Spanish study assesses the effectiveness of high-burden influenza vaccines in older adults – Salud Ediciones

A groundbreaking study in Spain will assess the effectiveness of high-burden influenza vaccines in older adults by randomizing real-world individuals into routine vaccination and using health records for monitoring and evaluation.

The Santiago Institute of Health (IDIS) and the Galician government health department are leading the study, involving 450,000 Galicians aged 65 to 79. This is the largest individual randomized study conducted by Spanish public health authorities.

Influenza is a highly contagious disease that can have serious health consequences, especially for high-risk groups such as the elderly and those with comorbidities. To combat this situation, vaccination is the most effective public health tool.

Experts note that this benefit is not only due to its effectiveness in preventing infection, but also because it plays a key role in reducing the likelihood of complications from the flu. Currently, influenza vaccines in Europe are evaluated based on immunogenicity results.

These results are important for measuring the immune system’s response after vaccination, but they don’t allow us to establish a causal link between the vaccine’s protective effects and variables such as reduced numbers of flu cases and hospitalizations in real life. and associated complications.

In this context, the Santiago Institute of Health (IDIS) and the Ministry of Health of the Government of Galicia have launched an innovative study aimed at measuring the real impact of the influenza vaccine in the age group 65 to 79 years.

As the study’s primary endpoint, the study will evaluate the relative effectiveness of standard-dose vaccine versus high-dose Efluelda® vaccine in reducing the risk of hospitalization for influenza or pneumonia. It will also consider hospitalizations due to cardiopulmonary disease, influenza or pneumonia, as well as hospitalizations and mortality from any cause as secondary variables.

This groundbreaking study in Spain combined two methods: randomization and real-life data collection. On the one hand, randomization will be used to assign participants to either the standard-dose vaccine or the high-dose vaccine, thus ensuring that the observed effects are due to the vaccine administered.

Outcome assessments, on the other hand, will be based on follow-up health records, which will help determine how many patients were admitted and for what reason. Dr. Federico Martinón Torres is coordinator of the Vaccine Research Unit at the San Diego Health Institute and the driving force behind the GalFlu study:

“In Galicia, the high-load vaccine is already routinely given to people over 80 years old and has been shown to be more effective. With this study we hope to evaluate the benefit in people aged 65 to 79 years, if this hypothesis is confirmed By confirming this, we will provide greater protection to this group of people who are considered vulnerable because of their weakened immune systems and greater risk of severe complications from infection with influenza.”

The real-life study involves more than 114,000 people aged between 65 and 79 years old and will be carried out during the next two influenza vaccination campaigns implemented by the Galician ministry. This is the largest individual randomized study ever conducted by a Spanish public health authority and is expected to provide strong evidence on important variables, such as reductions in hospitalizations and deaths due to influenza.

A recent study conducted in Spain revealed the estimated impact of seasonal influenza between 2008 and 2018. Among the key findings, the significant burden of influenza-related hospitalizations stands out, particularly among patients over 65 years of age, representing 65.6% of total hospitalizations and 81.1% of resulting direct costs.

Additionally, hospitalization rates for respiratory and cardiovascular disease diagnoses are approximately 4.5 times higher in this age group than in other groups. The hospitalization variable is of importance in health systems because it reflects not only the severity of influenza infection but also the severity of its consequences.

Hospitalization due to influenza not only imposes a significant economic burden in terms of medical resources and associated costs, but may also result in a loss of patient autonomy. Particularly for older adults, hospitalization may result in reduced independence and mobility, affecting quality of life and long-term care resources.

This link between hospitalization and loss of autonomy highlights the importance of preventive strategies, such as vaccination, to avoid hospitalization and its consequences for vulnerable populations. To address this challenge, some independent organizations recommend the use of high-load vaccines for people over 65 years of age because they contain higher concentrations of antigen (4 times more than standard doses) to stimulate a more robust immune response2-4.

These high-load vaccines are designed to better prevent influenza infection, with a relative efficacy of 24.2% higher than standard-dose vaccines; and associated complications, with a 27.8% reduction in hospitalizations for pneumonia and a 16.7% reduction in hospitalizations for cardiovascular complications. %, and the hospitalization rate for various reasons decreased by 8.2%5.

Likewise, in the DanFlu-16 trial, the trial evaluated the possibility of conducting a randomized study based on real-world data to investigate the effectiveness of a high-load vaccine versus a regular vaccine. The results showed that the Efluelda® vaccine reduced hospitalizations due to influenza or pneumonia in people aged 65 to 79 years by 64.4% compared with the standard dose vaccine. DanFlu-1 has allowed the launch of a large-scale randomized study that will be conducted during the next two anti-influenza campaigns in Galicia.

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