Early Outcome of Multisystem Inflammatory Syndrome in Neonates Diagnosed following Prenatal Maternal COVID-19 Infection: A Three-Case Series.

Background: The aim of this case series report is to evaluate the characteristics of multisystem inflammatory syndrome (MIS) in neonates following prenatal maternal COVID-19 infection.

Methods: We present a case series of three newborns (≤28 days of age) diagnosed with MIS due to the vertical transmission of SARS-CoV2 infection and admitted from 1 January 2021 to 1 June 2023. The inclusion criteria were negative RT-PCR-SARS-CoV-2 test in infants, initial negative IgM-SARS-CoV-2 in infants followed by the emergence of positive IgG-SARS-CoV-2 antibodies in infants and maternal COVID-19 infection in the third trimester of pregnancy. Patients enrolled in this case series were admitted due to acute febrile illnesses.

Results: All three cases occurred in patients born at a mean gestational age of 39 weeks and who were appropriate for gestational age. The mean age at admission was 18.3 days. Fibrinogen (>400 mg/dL) and ferritin (>120 mg/dL) were elevated above the upper normal limit. Elevated levels of myocardial biomarkers (D-dimers, N-terminal pro b-type natriuretic peptide troponin T and creatine phosphokinase myocardial band) were recorded, with normal heart function evaluated using echocardiography. All three patients were treated with antibiotics; one received intravenous immunoglobulin. A 4-week follow-up was completed in two patients when their myocardial biomarkers and ferritin were still elevated but lower compared with previous examinations. D-dimers levels were normalized in 2/3 patients.

Conclusions: Subclinical myocarditis was diagnosed as an early outcome in infants with MIS diagnosed postnatally due to the vertical transmission of SARS-CoV2 infection and may represent a new challenge for pediatricians in the pandemic era.