Fig. 1

Alpha-diversity between disease cases and healthy controls for each respiratory condition. Alpha-diversity (Shannon Index or Chao1 index) is shown between cases and controls for each study. Shannon diversity for both samples from the nasopharynx (N = 3223) (A) and the oropharynx (N = 1313) (B) was calculated, as well as Chao1 richness for the nasopharynx (N = 3223) (C) and the oropharynx (N = 1313) (D). Significant differences between cases and controls were determined by independent Student’s t-test, two-tailed p-value * = p < 0.05, ** = p < 0.01, *** = p < 0.001