The lower frequency of HLA-DQB1*06 in individuals experiencing breakthrough infection was observed both in the 41 individuals meeting the definition of primary symptomatic breakthrough infection (31.7% carrying HLA-DQB1*06 among those with the primary definition of breakthrough infection) and in the 66 individuals who were asymptomatic (28.8%) but not in the nine individuals who did not meet the primary definition of symptomatic breakthrough (66.7%) (Supplementary Table 7). Here, HLA-DQB1 is linked to infection.