Influenza vaccination is effective to prevent hospitalization due this virus in people over 65. This is the conclusion of the multicentre study coordinated by researchers from the CIBER of Epidemiology and Public Health (CIBERESP) and led by the researcher of the University of Barcelona, Ángela Domínguez.

The study, published in the journal Eurosurveillance assessed the effect of vaccination in the prevention of hospitalization of the elderly in two influenza seasons (2013-2014 and 2014-2015). The results placed a 36 % in the effectiveness of the vaccination to avoid symptoms that require general hospitalization, depending on the existence of high-risk medical conditions in patients, age of the subtype of virus.

In patients without other risky medical conditions, vaccination was a highly determining factor in hospitalization prevention. The effectiveness of the vaccine was 51 % for those patients, compared to the 30 % of effectiveness registered in patients who presented some risk conditions, including, among others, lung diseases, cardiovascular diseases, diabetes, chronic renal failure, haemoglobin disorder, immunodeficiency, neurological diseases and obesity.

Respecto a las diferencias de eficacia entre los distintos grupos de edad, la utilidad de la vacunación para prevenir ingresos a causa de la gripe fue mayor en pacientes entre 65 y 79 años (39 %) que en individuos a partir de los 80 años (34 %).

Regarding the differences in the effectiveness of the vaccine among the different age ranges, the usefulness of the vaccine to avoid hospitalizations due influenza was higher with patients aged between 65 and 79 (39 %) than in people aged over 80 (34 %).

The study also revealed differences in the effectiveness of the vaccine to prevent hospitalization in old people depending on the virus strain. The effectiveness was higher in the subtype A (H1N1) pdm09 (49 %) than in subtype A (H3N2) (26 %).

This multicentre study, carried out between December 2013 and March 2015 in a total of twenty Spanish hospitals from seven autonomous communities, included data from a total of 728 patients aged 65 or over 65 who had been hospitalized due influenza, and a control group of 1,826 people who were hospitalized for other reasons.

“Influenza vaccination is the most appropriate step to prevent morbidity and mortality related to seasonal influenza diseases”, said UB researcher Ángela Domínguez, supervisor of the study and assistant director of CIBERESP, who put emphasis on the fact that “results of this study show that influenza vaccination is effective in prevention of hospitalization of the elderly”.

Domínguez is the main researcher of the research group of Epidemiology, Prevention and Control of Communicable Diseases of the Faculty of Medicine and Health Sciences, and teaches at the Faculty of Pharmacy and Food Sciences.

At a global scale, seasonal influenza causes figures around the 3 and 5 million cases of serious illness, and between 250,000 and 500,000 deaths. In older patients, especially those with comorbidity, there is a higher risk of those virus complications requiring hospitalization. Studies undergone in the United States revealed that a 89 % of the deaths related to influenza were cases of people aged over 65, and a 11 % of old people deaths occurred during high peak seasons of influenza.