Tsang TK, Lee KH, Foxman B, et al. - Researchers examined if and how the nose/throat microbiome associate with susceptibility to influenza virus infection. They conducted a household transmission study including 115 index cases with influenza A(H3N2) or B infection and 436 household contacts; follow-up was performed for 9–12 days to recognize secondary influenza infections. Using high-performance sequencing, they identified and quantified bacterial species in respiratory swabs collected at enrollment. A 10-fold increase in the abundance in Streptococcus spp. and Prevotella salivae was linked with 48% and 25% lower susceptibility to influenza A(H3N2) infection, respectively. Whereas, there was 63% lower and 83% higher susceptibility to influenza B infection in correlation with a 10-fold increase in the abundance in Streptococcus vestibularis and Prevotella spp., respectively. These findings thereby support the association of nose/throat microbiome at the time of exposure with susceptibility to influenza infection and suggest the predictive value of microbiome for susceptibility, with the implication that microbiome could be modulated to decrease influenza infection risk, should these associations be causal.