[Clinical characteristics of 16 neonates infected with SARS-CoV-2 during Omicron variant outbreak].

Objective: To analyze the clinical characteristics of the neonates infected with SARS-CoV-2 during the Omicron outbreak in Shanghai 2022. Methods: In this retrospective case series study, all the 16 neonates with SARS-CoV-2 Omicron infection who were admitted to the neonatal unit in Shanghai Public Health Clinical Center from March 1st to May 31st, 2022 were enrolled. Their epidemiological history, clinical manifestations, nucleic acid cycle threshold (Ct) value and outcomes were analyzed. Based on maternal vaccination, they were divided into vaccinated group and unvaccinated group. Rank sum test and Chi-square test were used for the comparison between the groups. Results: Among the 16 neonates, 10 were male, and 6 were female. All the infants were full-term. The infection was confirmed at the age of 12.5 (8.0, 20.5) days. All the neonates had a history of exposure to infected family members, and thus horizontal transmission was the primary mode. Four infants were asymptomatic, 12 were symptomatic, and there were no severe or critical cases. The most common clinical manifestation was fever (11 cases), with the highest temperature of 38.1 (37.9, 38.3) ℃ and a course of 1-5 days. Other clinical manifestations included nasal obstruction (3 cases), runny nose (2 cases), cough (2 cases), poor feeding (2 cases), vomiting (1 case), and mild tachypnea (1 case). The complete blood counts of all neonates were within the normal range, and the C-reactive protein increased slightly in 1 infant. Chest imaging was performed in 2 infants, showing mild focal exudative changes. Nucleic acid turned negative (Ct value ≥35) within 7-15 days after diagnosis. All neonates fully recovered after supportive treatment, and the length of hospitalization was 13 (10, 14) days. In the telephone follow-up 2 weeks after discharge for all 16 cases, no infant showed reoccurrence of clinical manifestations or nucleic acid reactivation. Maternal vaccination was not significantly correlated with symptomatic infection or the persistence of positive nucleic acid result in neonates (all P>0.05). Conclusions: Horizontal transmission is the primary mode for neonatal SARS-CoV-2 Omicron infection. Neonatal infections are usually mild or asymptomatic, with good short-term outcomes. And their clinical manifestations and laboratory examinations are nonspecific.