CHENNAI: The findings of an ongoing study on vertical transmission of Covid-19 being conducted by government hospital doctors in Chennai so far suggest that the possibility of transmission of the virus in utero or through breast milk is low.
The study is being conducted by the Institute of Obstetrics and Gynaecology and Government Hospital for Women and Children in Egmore along with the King Institute in Guindy. So far, samples of amniotic fluid, placenta swab, and breast milk drawn from 548 mothers with Covid as well as samples from umbilical cord blood and nasal swabs of their babies have been tested.
"The study was started to see if Covid spreads from mother to baby in-utero or through breast milk. On the day of the delivery, we take four samples for testing - amniotic fluid, placenta swab, baby’s nasal swab, and umbilical cord blood. On the third day we send a sample of the breast milk and another sample from the nasal swab of the baby," said Dr S Vijaya, Director, Institute of Obstetrics and Gynaecology, Egmore. The study, which was initiated in July with ethics committee clearance, will continue till the last Covid case is reported at the Institute.
"Initially we thought to check if there is transmission through breast milk, but later decided to test all samples to rule out in utero transmission as well. We started getting positive pregnant patients only in the last week of April," she said.
According to Dr Vijaya, so far the breast milk sample from one patient, and the placenta swab from another patient have tested positive for the SARS-CoV2 virus that causes Covid. While three babies (unrelated to the mothers whose swabs were positive) tested positive for the virus on the first day, nasal swab tests on the third and fifth day were negative, she said.
"Similarly, when we tested the breast milk and placenta of the two patients respectively on the fifth day it was negative. So, these could be cases of false positives, sample contamination or improper collection of samples," Dr Vijaya said.
"Unless we have a decent number of breast milk samples or placenta swabs testing positive, we won’t be able to say the transmission is happening through breast milk or in utero," she explained, adding that based on the findings so far the possibility of transmission through those routes seemed low. It may be noted that so far studies in other countries have also suggested that the possibility of such vertical transmission is low.
While 46 babies tested positive for Covid on the third day, Dr Vijaya said, this suggested contact transmission rather than transmission in-utero or through breast milk.
“In these cases, the mother may not have worn the mask properly so the baby could have acquired the infection," she said.
So far the institute has handled 674 Covid pregnancy cases since April. Of them, samples from 548 mothers were tested with the remaining women either testing negative on the day of delivery or suffering miscarriages.