Babies born to mothers who received a Covid-19 vaccine during their pregnancy were significantly protected against the disease in their first six months of life, according to a local study by a team led by KK Women’s and Children’s Hospital (KKH).
However, the study found there was no conferred benefit to the newborns from mothers who were vaccinated prior to their pregnancy.
Associate Professor Yung Chee Fu, a senior paediatric infectious diseases consultant at KKH who led the study, said: “Maternal Covid-19 vaccination remains the most effective way to protect mothers and their pregnancies, as well as their newborns after delivery, against severe outcomes from Sars-CoV-2 infection.”
Prof Yung said Covid-19 vaccine protection against infection wanes over time as the level of antibodies fall. While more research is needed, he said “it is likely due to low levels of antibodies in the woman, resulting in limited transfer to the baby and hence the lack of protection observed”.
Babies in Singapore can only be vaccinated against Covid-19 from the age of six months. So any protection against the disease in the first half year of their lives has to be received from their mothers.
Singaporeans and permanent residents gave birth to almost 22,000 babies between January and September 2022. Only the 7,292 babies who had at least one parent diagnosed with Covid-19 in their first six months were included in the study. Of these, 1,272 babies were infected in the first six months of their lives.
The protection against being infected by Omicron XBB variants, which were the main strains circulating at that time, was 41.5 per cent for babies whose mothers were vaccinated during pregnancy.
Babies of mothers who received at least their third Covid-19 shot during their pregnancy had greater protection, at 77 per cent.
Said Prof Yung: “This study reinforces the importance of receiving boosters and keeping up to date with the recommended vaccination doses during pregnancy. Pregnant mothers cannot rely on the Covid-19 vaccines they received before pregnancy for protection of their newborns.”
The study, which followed the babies in their first half-year of life, was published on Friday on Jama Network Open, an international peer-reviewed, open-access, general medical journal by the American Medical Association.
Prof Yung said the study will help pregnant women make informed vaccination decisions regarding protecting their babies against Covid-19 infections.
Others involved in the study were from Singapore General Hospital, the National Centre for Infectious Diseases and the Ministry of Health.
Another study by KKH on long Covid in children and youth found that one in six under the age of 18 years suffered from long Covid following infection. The most common symptoms were runny nose, cough and fatigue. About half recovered within six months. Boys were 70 per cent more likely than girls to suffer from long Covid.
This study was carried out from October 2022 till January. It was published in the Annals – a journal of the Academy of Medicine, Singapore – on Oct 30.
KKH said this is one of the first such studies in Asia and the largest, with 640 participants.
Dr Li Jiahui, head of the paediatric infectious disease service at the hospital and lead author, said: “Vaccination reduces the risk of severe Covid-19 infection and can potentially confer some protection against long Covid in children and youths. Keeping up with the Covid-19 and influenza vaccinations remains important in guarding our health and well-being.”
Text: Salma Khalik/The Straits Times