Emergence of G186D mutation in the presence of R292K mutation in an immunocompromised child infected with influenza A/H3N2 virus, treated with oseltamivir.

An immunocompromised child with influenza A/H3N2 virus infection, treated with oseltamivir from day 1, had nasal swabs taken on days 1, 4, 7, and 10 of the illness. Pyrosequencing showed increasing proportions of viruses with R292K (neuraminidase gene) and G186D (hemagglutinin gene) mutations, resulting in a viral load rebound by day 10.