To ask whether SCV2 co-infection could equally compromise Mtb replication, K18-hACE2 Tg mice were first infected with Mtb. At a later stage of infection (day 170 post-Mtb) Mtb-infected mice and age-matched controls were then infected with a sub-lethal dose of USA-WA1/2020 SCV2 and monitored for 28 days after which bacterial burdens and lung pathology were assessed (Figure 2A). This evidence concerns the gene KRT18 and infection.