CALCA and COVID-19: Overall, multivariable Cox regression models of COVID-19-positive veterans with records of serum PCT values support that high serum values were positively associated with disease progression and severity for MV (adjusted HR, 1.80, 95%CI: 1.67–1.94) and in-hospital death (adjusted HR, 1.76, 95%CI: 1.66–1.87) (Fig 3).