COVID-19 Infection in Well-Appearing 30- to 90-Day-Old Infants with Fever without a Source.

Fever without a source (FWS) is common clinical status in the young infants. The aim of this study was to evaluate the clinical and laboratory findings of coronavirus disease (COVID-19) infection in well-appearing infants with FWS. Well-appearing febrile infants between 30 and 90 days who were evaluated as FWS in the pediatric emergency department and tested for COVID-19 were divided into two groups: COVID-19 (+) and (-). The clinical and laboratory findings of the patients were compared. The study included 95 febrile infants with FWS, and the mean age was 59.62 ± 16.82 days. The nasopharyngeal COVID-19 polymerase chain reaction test results of 29/95 (30.5%) patients were positive, while 66/95 (69.5%) were negative. The complaints of irritability and nasal congestion were found to be significantly more common in COVID-19-positive patients (p = 0.04 and p = 0.041, respectively). The hospitalization rate (p = 0.009), length of hospital stay (p = 0.026), initiation of antibiotic treatment (p < 0.001) and duration of antibiotic treatment (p = 0.036) were significantly lower in the COVID-19 (+) patients. The C-reactive protein (CRP, p < 0.001), absolute neutrophil count (ANC, p < 0.001), absolute lymphocyte count (ALC, p = 0.015), white blood cell (WBC, p < 0.001) and systemic immune-inflammation index (SII, p < 0.001) were found to be significantly lower in the COVID-19 (+) patient group. There was no significant difference between the groups in terms of neutropenia, lymphopenia or leukopenia. COVID-19 infection may present as an FWS. During the pandemic period, testing for COVID-19 among infants who were evaluated as FWS may reduce unnecessary hospitalizations and antibiotic treatments, and shorten hospital stays and duration of antibiotics.