Multiple Organ Dysfunction Secondary to Herpes Simplex Virus -1 Reactivation After Treatment With Dexamethasone and Sarilumab for Covid-19 Disease.

Introduction: The immunological response to the SARS-CoV-2 virus and the treatment of COVID-19 disease present a potential susceptibility to viral reactivation, particularly Herpes simplex virus-1 (HSV-1). Case Presentation: A 49-year-old female presented to hospital with severe COVID-19 pneumonitis and was given sarilumab and dexamethasone. She was intubated and ventilated in the intensive care unit (ICU) and initially demonstrated biochemical and clinical evidence of improvement. This was followed by a severe acute deterioration in respiratory, renal, and cardiovascular function, accompanied by a vesicular rash on the face. Polymerase chain reaction confirmed HSV-1 reactivation and treatment with acyclovir was commenced. After 49 days in ICU the patient was successfully weaned from all organ support, and she made a satisfactory recovery. Conclusions: HSV-1 reactivation is common in COVID-19 and likely contributes to poorer clinical outcomes. The mechanism causing susceptibility to viral reactivation is not clearly defined, however, the development of critical illness induced immunosuppression via dysfunction of interferon and interleukin pathways is a likely mechanism. This effect could be perpetuated with immunosuppressant medications, although further research is needed to characterise this phenomenon.