Fever without source as the first manifestation of SARS-CoV-2 infection in infants less than 90 days old.

Fever without source (FWS) in infants is a frequent cause of consultation at the emergency department, and the emergence of SARS-CoV-2 could affect the approach to those infants. The aim of this study is to define the clinical characteristics and rates of bacterial coinfections of infants < 90 days with FWS as the first manifestation of SARS-CoV-2 infection. This is a cross-sectional study of infants under 90 days of age with FWS and positive SARS-CoV2 PCR in nasopharyngeal swab/aspirate, attended at the emergency departments of 49 Spanish hospitals (EPICO-AEP cohort) from March 1 to June 26, 2020. Three hundred and thirty-three children with COVID-19 were included in EPICO-AEP. A total of 67/336 (20%) were infants less than 90 days old, and 27/67(40%) presented with FWS. Blood cultures were performed in 24/27(89%) and were negative in all but one (4%) who presented a Streptococcus mitis bacteremia. Urine culture was performed in 26/27(97%) children and was negative in all, except in two (7%) patients. Lumbar puncture was performed in 6/27(22%) cases, with no growth of bacteria. Two children had bacterial coinfections: 1 had UTI and bacteremia, and 1 had UTI. C-reactive was protein over 20 mg/L in two children (one with bacterial coinfection), and procalcitonin was normal in all. One child was admitted to the pediatric intensive care unit because of apnea episodes. No patients died.Conclusion: FWS was frequent in infants under 90 days of age with SARS-CoV-2 infection. Standardized markers to rule out bacterial infections remain useful in this population, and the outcome is generally good. What is Known: • Fever without source (FWS) in infants is a common cause of consultation at the emergency department, and young infants have a higher risk of serious bacterial infections (SBI). • The emergence of the new coronavirus SARS-CoV-2 could affect the approach to young infants with FWS in the emergency department. management of those children is a challenge because information about bacterial coinfection and prognosis is scarce. What is New: • SARS-CoV-2 infection should be ruled out in young infants (< 90 days of age) with FWS in areas with community transmission. • Bacterial coinfection rarely coexists in those infants. • Inflammatory markers were not increased in children without bacterial coinfection. • Outcome is good in most patients.