Thus, there are distinct differences that may explain the discrepancy in the findings from these studies compared to the current one: in the former study, lower IFNγ:IL-10 ratios in LCII cases may reflect competing responses to vaccination and to influenza virus when infection occurs within 4 weeks of vaccination [37]; in the latter study, the vaccine was well matched to the circulating A/H3N2 strain and influenza infection did not occur until after the 10-week post-vaccination time point [21]. Here, IL10 is linked to influenza.