Codon bias impacts expression and structure of clock proteins that underlie the in vivo circadian clock function in Neurospora, cyanobacteria, and Drosophila (Fu et al., 2016; Xu et al., 2013; Zhou et al., 2013), protein secretion in yeast (Pechmann et al., 2014), and virus/host interactions (including in COVID-19, Alonso and Diambra, 2020; Shin et al., 2015). The gene discussed is CLOCK; the disease is COVID-19.