CCR7 and COVID-19: Moreover, percentages of naïve CD45RO- CCR7+ CD28+ CD8+ T cells were markedly reduced in 29- to 79-year-old group of COVID-19 patients, suggesting an ongoing cytotoxic response during SARS-Cov-2 infection, but these differences were not evident in the over 80 group, probably due to the reduced pool of naïve T cells in the old individuals.