MUC1 and infection: Serum YKL-40 and KL-6 levels measured one month after the infection (visit 2) correlated negatively with FVC (L, YKL-40: r = -0.438, p = 0.022; % predicted, KL-6: r = −0.426, p = 0.024) and FEV1 (L, YKL-40: r = −0.476, p = 0.012; % predicted, KL-6: r = −0.407, p = 0.032) measured at visit 3 (Figure 7C–F).