Immunisation of young children against influenza — evidence review

Abstract

Influenza is a highly contagious viral infection and poses a serious burden, especially for children under 5 years of age due to an increased risk of severe illness and hospitalization. Influenza-related infant mortality during the pre-Covid period was reported annually. The highest mortality rate was regularly recorded among young children and especially children under the age of 6 months. Influenza vaccination in young children has been proven to be safe and effective. Influenza vaccination of young children not only protects this vulnerable age group, but is also an important way to reduce the transmission of influenza to others at risk, as well as reduce the use of healthcare services, including the use of antibiotics. Immunization against influenza in the current epidemiological conditions is especially relevant, since during the ongoing COVID-19 pandemic, it is impossible to predict the intensity and timing of the upcoming influenza seasonal rise. To prevent influenza in children, any licensed influenza vaccine that meets the indications is used, however, in modern conditions, the priority in influenza prevention is the use of quadrivalent vaccines that ensure the development of the most stable immune response against key strains of influenza viruses. Quadrivalent influenza vaccines include two influenza B strains of the Yamagata and Victoria B lines in addition to influenza A strains (H1N1 and H3N2). Studies have shown that immunization with the quadrivalent vaccine, including in young children, is well tolerated and effectively protects against any circulating and antigenically matched strains of influenza viruses. Russian-made quadrivalent inactivated full-cycle influenza vaccine for the prevention of seasonal influenza is the first quadrivaccine in the Russian Federation approved for use in influenza immunization of children from 6 months of age and pregnant women. The vaccine complies with all World Health Organization recommendations on the composition and amount of hemagglutinin of an influenza virus strain – it contains 15 μg of influenza virus hemagglutinin of each strain (А(N1N1), A(N3N2), B line Yamagata, B line Victoria); does not contain immunomodulators, adjuvants and preservatives; meets the immunogenicity criteria for inactivated influenza vaccines adopted in the European Union and the Russian Federation.

Keywords

• children
• influenza
• vaccination
• quadrivalent vaccine