TPH1 and COVID-19: Most notably, we see that patients with COVID-19 have a reduced ratio of circulating (c)Tfr to a network of antibody production-associated cells such as T-peripheral helper (Tph), plasma blasts, and CD11c+CXCR5− extrafollicular/atypical B cells, which in turn is strongly correlated with neutralizing antibody levels in the serum.