Pre-existing influenza specific nasal IgA or nasal viral infection does not affect live attenuated influenza vaccine immunogenicity in children.

In this study, we analysed banked samples from a study performed during the 2017/18 influenza season to investigate the role of pre-existing influenza-specific nasal IgA in children aged 6-14 years. Nasopharyngeal swabs were collected prior to LAIV immunisation, to measure pre-existing IgA levels and test for concurrent upper respiratory tract viral infections (URTI). Oral fluid samples were taken at baseline and 21-28 days after LAIV to measure IgG as a surrogate of immunogenicity. Antibody levels at baseline were compared with a pre-existing dataset of LAIV shedding from the same individuals, measured by RT-PCR. There was detectable nasal IgA specific to all four strains in the vaccine at baseline. However, baseline nasal IgA did not correlate with the fold change in IgG response to the vaccine. Baseline nasal IgA also did not have an impact on whether vaccine virus RNA was detectable after immunisation. There was no difference in fold change of antibody between individuals with and without an URTI at the time of immunisation. Overall, we observed no effect of pre-existing influenza specific nasal antibody levels on immunogenicity, supporting annual immunisation with LAIV in children. PMID: 33314126 [PubMed - as supplied by publisher]
Source: Clinical and Developmental Immunology - Category: Allergy & Immunology Authors: Tags: Clin Exp Immunol Source Type: research