Immune reminisces about a year in COVID-19 immunology, Steph’s receiving the Pfizer vaccine, and answers to listener questions about a challenge study with common cold CoVs, T cell exhaustion, how CD4 T cells control infections, and more.

Immune describes the striking loss of germinal centers in lymph nodes and spleen in patients with severe COVID-19, providing an explanation for short-lived humoral immunity and limited somatic hypermutation of antibodies to SARS-CoV-2.