Vaccinate children under 5 years of age against flu

To what extent is vaccinating children under 5 years of age against the flu wise? A new study has examined this question.

The authors of the study focused on the case of Spain. In October 2023, flu vaccination was recommended for the first time at the state level in Spain in the pediatric population aged between 6 months and 5 years.

The study has been carried out by a team led by research staff from the Networked Biomedical Research Center for Epidemiology and Public Health (CIBERESP) and the Networked Biomedical Research Center for Infectious Diseases (CIBERINFEC), attached to the Carlos III Health Institute. (ISCIII).

The study concluded that this vaccination prevented 70% of flu infections that would have had to be treated in primary care, and 77% of hospitalizations due to flu, among vaccinated minors.

Based on the results of the study, which are consistent with those of other previous studies, the research team recommends continuing to promote flu vaccination coverage in this age group.

The study was carried out on 1,666 children under 5 years of age, of whom 1,364 were treated in health centers and 302 were hospitalized.

Together, the results show good effectiveness of the vaccine in both settings, although the small number of hospitalizations due to influenza in this pediatric population provides lower certainty in the estimates related to hospital admissions. In health centers, the good effectiveness of the vaccine achieved against the A(H1N1)pdm09 subtype stands out, which circulated predominantly throughout the 2023-2024 season and, specifically, against clade 5a.2a, despite the fact that clade 5a.2a .1 was included in the vaccine recommended by the World Health Organization (WHO).

Viral particles of a strain of influenza, captured by electron microscope. (Image: US National Institute of Allergy and Infectious Diseases (NIAID))

The study was carried out with data from the Acute Respiratory Infection Surveillance System (SiVIRA), which is coordinated by the ISCIII in collaboration with the Ministry of Health and the autonomous communities and cities. The main authors of the work are Gloria Pérez Gimeno, Clara Mazagatos and Susana Monge, from the National Center for Epidemiology (CNE) of the ISCIII, and Francisco Pozo from the National Center for Microbiology (CNM), in turn research staff at the CIBER centers. Professionals from the Health Departments of the autonomous communities and cities have also participated.

It is estimated that around the world there are 109 million influenza virus infections annually in children aged 0 to 5 years, an age group at risk of suffering serious illness and which in Spain has the second highest rate of admissions. hospitalizations for flu, only below that of people aged 65 or older. Furthermore, children under 5 years of age play a key role in the community circulation of the virus and in the amplification of flu epidemics.

The study is titled “Effectiveness of influenza vaccines in children aged 6 to 59 months: a test-negative case–control study at primary care and hospital level, Spain 2023/24”. And it has been published in Eurosurveillance, the academic journal of the European Center for Disease Prevention and Control (ECDC). (Source: ISCIII)