Children with a rapid response to antibiotic treatment, and therefore likeliness of pneumococcal infection, revealed significantly higher PCT levels than the ones with delayed response (i.e., >48 h) [median (IQR) 3.7 (1–9.4) vs. 0.7 (0.2–2.9), p = 0.002] (34). The gene discussed is CALCA; the disease is pneumococcal infection.