Seroprotection against measles in previously vaccinated children with difficult-to-treat nephrotic syndrome

Abstract

Background Children with nephrotic syndrome (NS) are vulnerable to infections. Measles infection is an important cause of morbidity and mortality in immunosuppressed children. A suboptimal seroprotection against measles has been shown in immunocompromised children. There is limited published literature on measles immunity in children with difficult-totreat nephrotic syndrome (DTNS). We compared the proportions of children with DTNS and healthy controls who were seroprotected against measles. Methods This was a cross-sectional study. Measles-specific IgG antibodies of 108 children with DTNS (3 to 10 years of age) and an equal number of age-matched healthy controls were measured. All children had received two doses of measlescontaining vaccine at 9-12 and 16-24 months of age under routine immunisation programme. Serum measles IgG antibody titres were measured by indirect ELISA. The assay results were interpreted as (1) > 11 NTU (NovaTec Units), positive/seroprotective titres; (2) 9-11, equivocal; and (3) < 9 NTU, negative. Inter-and intra-group comparisons were made to identify the disease characteristics related to seroprotection status. ResultsThe proportion of children with protective anti-measles antibodies (n = 70, 65%) was significantly lower in DTNS as compared to controls (n = 88, 81.48%) (p = 0.005). Their median [IQR] antibody titres were also significantly lower than those in controls (14.1 [14] NTU vs. 18.3 [15.2] NTU (p = 0.001). The age, gender, clinical subtype, duration of disease, and type of immunosuppressive therapy were not significantly different between seroprotected and non-seroprotected children with DTNS. Conclusion A significantly lower percentage of fully vaccinated children with DTNS were seroprotected against measles compared to healthy controls.