Importantly, another group reported that the minor C allele of rs12252 in the Caucasin population is much more prevalent in Han Chinese and Japanese and is associated with disease severity in patients with pH1N1/09 IAV infection (Zhang et al., 2013)

IFITM Genes, Variants, and Their Roles in the Control and Pathogenesis of Viral Infections

Additional research about this Han Chinese vulnerability is noted in an article "Genetic variants in IL1A and IL1B contribute to the susceptibility to 2009 pandemic H1N1 influenza A virus"

Chinese population-attributable risk for severe influenza infection was ten-fold greater than Northern European population-attributable risk because of the high frequency of rs12252-C in Han Chinese [4]. Meanwhile, the SNPs in TLR3 [5], CD55 [6], C1q and FCGR2A [7], TNF [8, 9], LTA, IL8 and IL1B [9] were suggested to be connected with the severity of A(H1N1)pdm09 virus infection.

...

Here, we found a significantly high frequency of IL-1B rs1143627 allele C in A/H1N1 patients, suggesting the hosts with allele C were more susceptible to this virus infection. Importantly,the frequency of the rs1143627 allele C is quite rich in Han Chinese (minor allele frequency = 0.476). Thus, elucidation of the underlying mechanism of the polymorphism of rs1143627 is of great importance for in-depth understanding of the susceptibility of influenza in Chinese population

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3750637/

https://www.frontiersin.org/articles/10.3389/fmicb.2018.03228/full