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.

中文翻译：

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外观良好的 30 至 90 日龄婴儿因无源发热而感染 COVID-19

无源发热（FWS）是小婴儿常见的临床状态。本研究的目的是评估外观良好的 FWS 婴儿中冠状病毒病 (COVID-19) 感染的临床和实验室结果。在儿科急诊科评估为 FWS 并进行 COVID-19 检测的 30 至 90 天的外观良好的发热婴儿被分为两组：COVID-19 (+) 和 (-)。比较患者的临床和实验室检查结果。该研究包括 95 名 FWS 发热婴儿，平均年龄为 59.62 ± 16.82 天。29/95（30.5%）患者鼻咽部COVID-19聚合酶链反应检测结果为阳性，66/95（69.5%）为阴性。在 COVID-19 阳性患者中发现易怒和鼻塞的主诉更为常见（p = 0. 04 和 p = 0.041，分别）。COVID-19 (+) 患者的住院率 (p = 0.009)、住院时间 (p = 0.026)、开始抗生素治疗 (p < 0.001) 和抗生素治疗时间 (p = 0.036) 显着降低患者。C 反应蛋白 (CRP, p < 0.001)、中性粒细胞绝对计数 (ANC, p < 0.001)、淋巴细胞绝对计数 (ALC, p = 0.015)、白细胞 (WBC, p < 0.001) 和全身发现 COVID-19 (+) 患者组的免疫炎症指数 (SII, p < 0.001) 显着降低。在中性粒细胞减少、淋巴细胞减少或白细胞减少方面，各组之间没有显着差异。COVID-19 感染可能表现为 FWS。疫情期间，