Every year, 5 to 20% of the world's population is infected with the flu virus. A new epidemiological study shows that, although there are seasons in which the flu vaccination is ineffective, it can reduce the symptoms of the disease.
If flu vaccination is ineffective in the prevention of influenza, this may have additional effects in reducing the severity of the disease, according to a study conducted by the Carlos III Institute for the Epidemiology, Infectious Disease Prevention and Control and Center Biomedical Research on the Epidemiology and Public Health Network (CIBERESP).
Job published in the journal Eurosurveillance, led by professor Àngela Domínguez of the University of Barcelona, Department of Medicine. The researchers from the Catalan Public Health Agency, Lleida Biomedical Research Institute and the Barcelona Healthcare Agency also participated.
People who are already infected with the virus or receive a vaccine could benefit from the pre-existing cytotoxic T-lymphocyte memory
Every year, between 5 and 20% of the world's population is infected with influenza viruses, causing 3 to 5 million serious cases and between 300,000 and 500,000 deaths worldwide. The new work analyzes the effectiveness of influenza vaccination in order to reduce the severest influenza outcomes: in intensive care units or in the death of patients for whom the vaccine has not eliminated the infection.
To achieve this, we have investigated all cases of severe influenza that were admitted to twelve Catalan hospitals between 2010-2011. Annual Influenza Seasons and 2015-2016. In the year when 1777 patients were hospitalized for eighteen years of age, 591 of them were hospitalized. ICU and 223 died.
Most benign symptomatology
The results indicate that vaccination was less frequent (21.2%) in those requiring hospital admission or death than other patients with more favorable symptoms, of which 29.7% were vaccinated. Thus, the effectiveness of vaccination to prevent hospital admission or the death of all patients who were hospitalized with influenza was 23%, and in particular in the group over 65 – 44%.
"For these percentages, we need to add vaccine efficacy to prevention of influenza.These data intensify seasonal flu vaccination for all those who are more likely to have severe forms of influenza, such as people aged 65 and people with other underlying diseases, where the vaccine is often not enough to prevent the infection, "says the authors.
Researchers indicate that the role of the immune system could be to explain the possible outcomes. "People previously infected with the virus or who received influenza vaccine could at least partially benefit from the pre-existing cross memory of cytotoxic T-lymphocytes, which would reduce the severity of the infection, even if there is no protective antibody," concluded.