The first European data on the effectiveness of the influenza vaccine they bring to light a protection rate between an 32 and a 43% against influenza A in primary care, and between 34 and the 38% in hospitalized elderly people, according to the results of an international study in which six European countries participated, including Spain through the Center for Biomedical Research in Epidemiology and Public Health Network (Ciberesp).
During this season there has been in Europe a predominant increase in influenza A, according to the data collected by the Scientific Information and News Service (SINC). The 99,5% of the cases in all the combined studies were positive for this type of virus, with mixed circulation of subtypes A (H3N2) and A (H1N1) pdm09. In Spain, these data are similar to the European average. Even so, experts insist that immunization "remains the most effective preventive measure" against this disease.
Each year, the flu vaccine is designed from three strains of the virus. When the vaccine is administered with the viruses, the immune system generates antibodies that protect against those microorganisms included in the biological preparation. The World Health Organization (WHO) is in charge of determining, through a large global network of influenza surveillance laboratories, which strains of the virus are the most circulating and deciding with which of them the vaccine will be manufactured, that is renewed every season. This entire process takes several months, and the WHO is in charge of clarifying which microorganisms it will include in the immunization according to the viruses that have circulated the most the previous season. Therefore, the origin of the low efficacy of the vaccine this year lies, according to the experts, in two elements: the two strains that circulate the most respond little or nothing to immunization because one of them has suffered a mutation and the other is not in the vaccine.
According to the National Center of Epidemiology and National Center of Microbiology of the Carlos III Health Institute, the data obtained reveal that Vaccination remains the most effective preventive measure against influenza, while supporting the need for more effective interventions against subtype A (H3N2) in all age groups. "These results, therefore, reinforce the national and international recommendations for influenza vaccination, especially in groups at high risk of complications from influenza, such as those older than 64 years," they added.
