Figure 3. Correlation between telomere length, age and COVID-19 severity. (A–D) Pearson correlation analysis between telomere length (A, C, D) or percentage of short telomeres (<3 kb) (B) and age or COVID-19 severity in PMBC samples. In (A, B) telomere length was analysed by HT-QFISH and in (C, D) by TRF and PCR, respectively. The severity score was established by assigning values of 1, 2, 3, 4 for mild, moderate, severe, and acute, respectively (see Materials and Methods). The Pearson r coefficient and the P values are indicated.