Immunogenicity of influenza vaccination in children with idiopathic nephrotic syndrome

The present study shall be conducted at the pediatric nephrology clinic, of a tertiary care centre hospital, JIPMER, Puducherry from June 2025 to June 2027 after obtaining prior approval from the Institutional Ethics Committee. The study will be carried out in accordance with the World Medical Association (WMA) Declaration of Helsinki ethical principles for medical research involving human subjects.  Written informed consent shall be obtained from the parents prior to enrolment for the study. This study will be a prospective study in which children and adolescents with idiopathic nephrotic syndrome fulfilling the inclusion criteria shall be enrolled. Children and Adolescents aged 1-18 years with idiopathic nephrotic syndrome (INS) satisfying the inclusion and exclusion criteria (attending the Pediatric nephrology clinic) shall be recruited for this study. The enrolled participants shall receive the intervention Northern hemisphere quadrivalent Inactivated Influenza vaccine (IIV4) with longer expiry date, composition of vaccine as per Government of India guidelines for the season. The vaccine available in the prefilled syringe, 0.5 ml will be given as deep intramuscular injection in deltoid. For children aged below 8 years, 2 doses 4-weeks apart are recommended if they are receiving the IIV for the first time, while older children shall receive a single dose of vaccine. The vaccine shall be administered by the unblinded study staff.To measure the immunogenicity of vaccine, the change in the level of Hemagglutinin Inhibition Antibody (HAI) titres will be measured and expressed in Geometric Mean Titres (GMT). HAI assay will be standardized with 8HA units/50ml of all four standard vaccine antigens individually. The standard vaccine antigens will be procured from Influenza resource centre, National Institute for Biological Standards and Control (NIBSC) UK. Serum sample will be diluted two-fold in 96 well plated followed by addition of standard antigen to each well. Finally, 1% turkey RBC will be added to determine the HAI titre for each sample. The mean change in GMT titres at day 30, 6 months, and 1 year, shall be compared with baseline GMT in all study participants. The seroconversion is defined as HAI titres > 1:40, the level which gives 50% protection against lab confirmed influenza in vaccine recipients. The proportion of participants achieving and maintaining seroconversion at day 30, 6 months, and 1 year, will be compared.