At day 22, the seroprotection rates ranged between 96% and 99% for all four vaccine strains in the QIVc and TIV1c/TIV2c groups. test vaccine, Vaxiflu-4, showed non-inferiority in terms of immunogenicity and security when compared with research vaccine, Fluarix Tetra (Clinical trial registry number: CTRI/2022/05/042514). KEYWORDS:Influenza, pediatric vaccination, security profile, tetravalent inactivated vaccine, Immunogenicity == Introduction == Influenza is usually a significant global cause of morbidity and mortality in children, with annual seasonal influenza vaccination programmes implemented to reduce the burden of the disease.1,2However, the Memantine hydrochloride effectiveness of these programmes varies, with some national programmes recommending universal influenza vaccination, while most Western countries focus on high-risk groups. Children under two years of age and those with certain underlying medical conditions are considered at greater risk of influenza-related complications. Worldwide, influenza is usually a common disease with an estimated yearly attack rate of 510% in adults and 2030% in children.3,4Influenza was found to be highly prevalent in children less than 5 years, particularly those under two years. Data released in India indicate that it accounts for 510% of all cases of acute respiratory infections (ARIs).5A community-based study Memantine hydrochloride conducted in northern India estimated the annual incidence of influenza episodes among children under the age of one and two with ARIs to be 180 and 178 per 1000 children, respectively.6 Monovalent influenza vaccine was launched in 1930 and was considered the 1stgeneration of influenza vaccines. Split virion trivalent was launched in the 1960s, followed by subunit trivalent in the 1980s, and were generally considered as the 2ndand 3rdgenerations, respectively.7Quadrivalent split virion vaccine was launched in 2012 in the United States and is considered the 4th-generation quadrivalent influenza vaccine (QIV).8The Indian Academy of Pediatrics recommends that all children under the age of five receive an annual influenza vaccination.9Globally, two types of inactivated influenza vaccines are available: split virion and subunit vaccines. In India, currently only two influenza vaccines are licensed and recommended for immunization in children and adults, which include QIV and trivalent inactivated influenza vaccine (TIV).10TIVs are composed of two influenza A strains (A/H1N1 and A/H3N2) and one strain of influenza B, whereas QIVs are composed of two B lineages (Victoria and Yamagata). QIVs offer additional protection against influenza and reduce disease-related complications, along with cost.11Since the 1970s, children under the age of three have been administered inactivated influenza vaccines at a reduced dose of 7.5 g per antigen, which is half the standard dose for Memantine hydrochloride older children and adults.12This reduced dose was implemented to minimize the occurrence of febrile convulsions and reactogenicity associated with the whole virus vaccines that were prevalent at the time. Children, however, react differently to this reduced dosage, particularly when it comes to vaccination strain B.13Specifically, compared to older or vaccine-primed youngsters, children under the age of three exhibit a reduced immune response when it comes to vaccinations.14It may be possible to enhance the immunological response in this susceptible populace by switching to a double-dosage regimen, which uses the same dose for adults and children three years of age and older.15Given that the risk of illness is usually inversely correlated with the post-vaccination hemagglutination inhibition (HI) antibody titer, it is anticipated that increasing the immunogenicity of inactivated influenza vaccinations for young children will enhance BMP2B their efficacy. Furthermore, several clinical studies have shown that despite the higher antigen weight and volume in the 0.5 ml and 0.25 ml doses of inactivated influenza vaccines, their reactogenicity profiles are indistinguishable in children under three years of age.16Numerous studies have reported comparable immunogenicity profiles of influenza vaccines Memantine hydrochloride with either reduced antigen content or higher antigen content in children less than 35 months of age. Worldwide, several inactivated influenza vaccines have now been approved in a dose of 0.5 ml (containing 15 micrograms per antigen) for routine influenza vaccination in children aged 635 months. Further, a tetravalent (quadrivalent) inactivated influenza vaccine (Vaxiflu-4 vaccine from Zydus Lifesciences Limited, made up of 15 micrograms per antigen) has been already approved in India Memantine hydrochloride for use in children 35 months of age and adults.17 Co et al. reported that split-virion influenza vaccines stimulated a stronger cellular immune response to influenza than subunit vaccines.18In all age groups, Split virion vaccine is better.