Noticing the disappearance of Slamf9+ and Cd38+ macrophages after SARS-CoV-2 clearance at d14 (Fig. 3b; Supplementary Fig. S3c), we speculated that the specific transcriptional state of Slamf9+ macrophages may be induced by engulfment or infection of SARS-CoV-2, which needs to be further investigated. The gene discussed is SLAMF9; the disease is infection.