Letter to the editor: Vitamin D levels in acute illness and clinical severity in COVID-19 patients.

We would like to comment on the recently published article titled: "Circulating Vitamin D levels status and clinical prognostic indices in COVID-19 patients" by Ricci et al. The authors grouped the patients into two groups according to the vitamin D levels measured at the time of admission into the hospital and reported that lower vitamin D levels are associated with elevated D-dimer and IL-6 levels, low CD4/CD8 ratio and compromised clinical findings with elevated LIPI and SOFA scores. However, review of recent literature shows this association to be debatable. The 25-hydroxyvitamin D levels in the initial phase of critical illness have been reported to drop rapidly and hence consideration of the time of measurement from symptom onset would have enhanced the clinical relevance of these findings. Inferred association between vitamin D levels and disease severity based on SOFA score in COVID-19 patients, needs to be further explored in the light of the recent literature which casts doubt on using SOFA score at admission to predict mortality in COVID-19.

A Case of COVID-19 Infection With Delayed Thromboembolic Complication on Warfarin.

Novel coronavirus disease 2019 (COVID-19) pandemic has posed an unprecedented threat to humanity with more than eight million infections and 450,000 deaths reported worldwide so far. The spectrum of the disease varies from mild asymptomatic infection to severe disease with rapid progression to acute respiratory distress syndrome and multiorgan failure. It is associated with a prothrombotic state and hence there is a risk of thromboembolic complications in critically ill patients, even after recovery. However, the duration of prothrombotic risk after recovery is yet to be determined. We present the case of a 78-year-old man with a history of atrial fibrillation on warfarin who had been recently discharged to a nursing home after recovering from COVID-19 pneumonia and presented to the emergency department a month later with worsening shortness of breath and cough. He was found to have worsening respiratory failure with multiple segmental pulmonary emboli, despite being on warfarin, and supratherapeutic international normalized ratio (INR). He required mechanical ventilation and was started on steroids and therapeutic enoxaparin anticoagulation. This case highlights the risk of delayed thromboembolic complications in patients with COVID-19 infection and the need to identify the subgroup of patients with a higher risk of thromboembolism, such as discharges to nursing homes and those in need of oxygen requirement; and those with underlying comorbid conditions that may require anticoagulation for a longer duration. The role of heparin is being increasingly investigated in patients with COVID-19 infection; however, the role of other anticoagulants such as warfarin is yet to be defined.