Prolonged fever and hyperferritinaemia: a puzzling diagnosis of neonatal herpes simplex virus infection during COVID-19 pandemic.

Neonatal herpes simplex virus (HSV) infection is rare, with an estimated incidence of 3.58 per 100 000 live births in the UK and should be suspected in any newborn with fever and bacterial culture-negative sepsis. We describe a case of a previously well full-term male neonate who presented with persistent fever and elevated ferritin level that was carried out during the era of the COVID-19 pandemic as part of SARS-CoV-2 panel investigations. Despite the initial negative HSV serology, HSV-1 PCR from a scalp lesion returned positive. He made a full recovery after acyclovir therapy. This case highlights the importance of maintaining a high clinical index of suspicion of HSV infection in any febrile neonate even with absence of maternal history and negative serology, particularly if associated with hyperferritinaemia. We also address the challenge of interpreting inflammatory biomarkers' results for SARS-CoV-2 infection in neonates.