 The study assessed the effectiveness of a trivalent influenza vaccine in preventing influenza-like illness among nursery school children in Suzhou, China during the 2015-2016 season. The results showed that the vaccine was not effective in preventing influenza A, H1N1, PDM09, and there was a moderate but not significant VE for this lineage. Additionally, mismatching of B lineage may have compromised vaccine effectiveness during the study period. Further research is needed to inform policy related to quadrivalent influenza vaccine licensure in China.