CAMP and infection: The LL‐37 expression level was significantly upregulated following infection with original SARS‐CoV‐2 or Delta variant but not Omicron BA.1 compared with that of vehicle control on 3‐day post infection (dpi) (Figure 1B), the time which is reported as the peak viral loads after infection with SARS‐CoV‐2 for mice [38, 39, 40], corresponding to the compromised inhibition of Omicron variants by LL‐37.