Coinfection of SARS-CoV-2 and multiple respiratory pathogens in children

To the Editor,

The COVID-19 outbreak occurred in Wuhan City of China in December 2019. Within 3 months, the disease has swept the world resulting in 191,127 confirmed cases and 7807 deaths in more than 150 countries and territories [1]. COVID-19 has been reported predominantly in adults, particularly in those with chronic comorbidities [2], [3]. A small number of cases of COVID-19 have been reported in children; therefore, children are widely believed to be not susceptible to COVID-19 [4], [5]. Here we report two cases of COVID-19 in children who were coinfected with human respiratory viruses and Mycoplasma pneumoniae (MP) in China.

A total of 161 hospitalized children (≤14 years of age) with positive respiratory virus polymerase chain reaction (PCR) were enrolled in a retrospective study of respiratory infections in the pediatric ward of a class A tertiary comprehensive hospital in Wuhan, China from December 1, 2019 to January 16, 2020. Nasopharyngeal swab, sputum or bronchoalveolar lavage fluid specimens were tested for respiratory viruses by real-time PCR (RT-PCR) or multiplex PCR combined with capillary electrophoresis. Clinical presentation, laboratory findings and radiological features were collected from electronic medical records. The study was approved by the Ethics Committee of the Renmin Hospital of Wuhan University.

A total of 239 positive targets of pathogens were detected in 161 children. The highest proportion of pathogens were human respiratory syncytial virus (HRSV) (in 76 patients [31.80%]) and influenza A virus (in 72 patients [30.13%]). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19, was detected in two patients and accounted for 0.84%.

SARS-COV-2, HRSV and human metapneumovirus (HMPV) were found in the bronchoalveolar lavage fluid of patient 1, and SARS-COV-2, MP and HMPV were found in the bronchoalveolar lavage fluid of patient 2. The two patients stayed in different pediatric wards. Clinical characteristics of these two children with COVID-19 are shown in Table 1.

Patient 1 was admitted to the hospital on December 28, 2019, for fever and dry cough that occurred a few hours ago. Routine blood tests revealed a leukocyte count of 16.81×10⁹ cells/L (reference range 3.5–9.5×10⁹ cells/L), neutrophil count of 14.02×10⁹ cells/L (reference range 1.8–6.3×10⁹ cells/L) and lymphocyte count of 2.05×10⁹ cells/L (reference range 1.1–3.2×10⁹ cells/L). Inflammatory factor investigations revealed elevated C-reactive protein (CRP) level (46.92 mg/L, normal: 0–10 mg/L) and procalcitonin (PCT) level (0.11 ng/mL, reference range 0–0.10 ng/mL). Blood culture and sputum culture were all negative. Chest computed tomography revealed a ground-glass opacity in the lung. Due to her oxygen saturation of 70% in ambient air, this patient was diagnosed with severe pneumonia and was admitted to the intensive care unit (ICU). After 2 weeks of treatment with antiviral agents, antibiotic agents and supportive therapies, she was discharged smoothly with no residual symptoms.

Patient 2 was admitted to the hospital on December 29, 2019, for fever, cough and vomiting the day before. Laboratory investigations showed the leukocyte, neutrophil and lymphocyte counts were in the normal range. Serum amyloid A was increased (41.20 mg/L, normal: 0–10 mg/L), but PCT and CRP levels were normal. After 11 days of treatment with supportive therapies and antibiotic agents, she was on the mend and was re-examined for all inflammatory indexes and all showed normal, and she was discharged from the hospital.

In this retrospective study, we demonstrate that children are not only susceptible to SARS-CoV-2 infection, but they can be coinfected with SARS-CoV-2 and multiple respiratory viruses and bacterial pathogens including HRSV, HMPV and MP in China. Children were reported to have milder illnesses and shorter durations compared to adults [5]. Our study indicated that one of the two children needed ICU, indicating the child had severe symptoms. Because the number of cases of coinfection is small, we cannot determine whether coinfection of SARS-CoV-2 with other viruses or bacteria aggravates the condition. Our study indicated that coinfection of SARS-CoV-2 and HRSV, HMPV or MP in children occurs, suggesting that children with respiratory infection should be screened for SARS-CoV-2 and other respiratory viral and bacterial pathogens during the COVID-19 pandemic to prevent missed diagnosis and transmission of SARS-CoV-2. The prevalence of SARS-CoV-2 coinfection with other pathogens is also unclear in adult COVID-19 patients, as there has only been a case report of a 69-year-old man who was coinfected with SARS-CoV-2 and influenza A virus in China [3]. Our study indicates that COVID-19 patients should be investigated for coinfection with other respiratory viruses and bacterial pathogens.