CXCR5 and COVID-19: The frequencies of spike (S)-specific cTfh cells (CD3+CD4+CD45RA–CXCR5+) are consistently elicited after S peptide stimulation in convalescent COVID-19 cases and exhibit a clear phenotypic bias to aCCR6+CXCR3-cTfh17 cell phenotype; however, neutralizing activity is inversely correlated with S-specific cTfh17 cell frequencies but positively correlated with S-specific cTfh, cTfh1 (CCR6-CXCR3+) and cTfh2 (CCR6-CXCR3-) cell frequencies (147).