A genomic analysis of more than 45,000 complete SARS-CoV-2 genome sequences was published in this week's Communications Biology, revealing the existence of multiple substrains of the virus in the US, some of which have the potential to become more infectious. In the study, researchers from Michigan State University use SNP calling and other techniques to analyze the SARS-CoV-2 genomes and uncover evidence of four substrains and 11 prevalent missense mutations in the US. Notably, one of mutations is associated with a greater immune response in infected women versus infected men, and two others are likely to strengthen the folding stability of the SARS-CoV-2 spike and ORF8 proteins, which are used by the virus to infect and adapt to its host. Based on the substrains' different mutation profiles, two of them appear to have the potential to become more infectious, the study's authors write.