One of the youngest documented cases of established vertical transmission of SARS-CoV-2 infection in a premature neonate was reported in the latest edition of BMJ journal by Dr David et al from Malaysia.

A 39-year-old primigravida with underlying advanced adenocarcinoma of the colon was admitted at a tertiary care center for a planned premature Caesarean section and tumour resection at 29weeks gestation due to impending rupture of the tumour. Antenatal steroids for administered for fetal lung maturity.

In the meanwhile mother developed fever and cough on day 4 of admission. RTPCR of nasopharyngeal swab was positive for SARS-CoV2 and chest radiograph showed signs of pneumonia. Her elective C-section was postponed on diagnosis of COVID-19 infection. However, the mother developed premature contractions and preterm labour rapidly ensued. A male infant was born via spontaneous vaginal delivery at 29 weeks plus 5days gestation with a birth weight of 1100g.

APGAR was 9 at one minute and five minutes of birth and neonate was shifted to neonatal intensive care unit for stabilization in a separate negative suction room. There were no other cases of COVID-19 in the unit, no visitors allowed and all healthcare workers who attended to the child remained asymptomatic in the 2 weeks following delivery. The infant required noninvasive continuous positive airway pressure ventilation. During the due course at 12 hours of life he developed worsening respiratory distress requiring mechanical ventilation and surfactant therapy.

A nasopharyngeal swab from neonate for RT-PCR obtained at 2 hours of life was positive for all 3 SARS-CoV-2 target genes. The repeated respiratory sample with a tracheal aspirate remained positive 24 hours later. Chest X-ray findings were consistent with hyaline membrane disease. Neonatal serology at birth for SARS-CoV2 specific IgG and IgM was negative, however the infant demonstrated seroconversion for IgG and IgM on day 14 of life. His white cell count was normal at birth but he developed neutropenia, lymphopaenia and thrombocytopaenia by the third day of life.

Mechanical ventilation was required for 14 days and gradually weaned to room air by day 50 of life. Cranial USG showed bilateral grade 2 IVH with no subsequent progression. In view of extreme prematurity he was started on total parenteral nutrition(TPN) ,while gradually introducing enteral formula feeds. . No antivirals or corticosteroids were given to the infant. He was discharged home on day 54 of life. Ophthalmology screening on discharge was normal.

COVID-19 infection in pregnancy leads to an increased risk of complications to both mother and baby. Pregnant women with COVID-19 are more vulnerable to severe disease and are more likely to experience premature delivery. Vertical transmission of the virus is thought to occur through several mechanisms: (1) in utero via hematogenous transfer across the placenta, aspirated amniotic fluid or (2) intrapartum via exposure to infected maternal blood or vaginal secretions.

Despite vertical transmission of SARS-CoV-2 being a rare occurrence, it is a plausible route of infection for this case and the points favouring are:

-The infant did not receive breastmilk, ruling out this route

-Sampling was done after cleaning and shifting the neonate to NICU ,hence reducing risk of contamination from maternal vaginal secretions.

-Sample from tracheal aspirate on day 2 showed increasing viral shedding inferred by cycle threshold values thus indicating ongoing replication.

-The infant's SARS-CoV-2 specific IgG at birth was negative

All these were compatible with the recently proposed definition for vertical transmission of SARS-CoV-2 by the WHO.

The neonate did not experience a stormy course other than respiratory distress which is most likely attributed to hyaline membrane disease. Management of COVID-19 in premature neonates includes ventilation, fluid balance and supportive measures.In this case the struggles were compounded by the need for stringent airborne and contact precautions for an extended duration, considering the expected prolonged stay in the NICU.

RTPCR was positive at fifth week of life , however the exact duration of replication-competant viral shedding is unknown. There is need for further studies to determine the duration of infectivity in neonates and the longterm outcomes

Source: NG DC, Chin L, Choo PPL, et al COVID-19 in a premature infant BMJ Case Reports CP 2021;14:e243783