Flu vaccine safe for pregnant women, fetuses, Ottawa study shows
CBC News
July 10, 2019

Study followed more than 100K newborns until age 5

An Ottawa study shows no link between pregnant women receiving the H1N1 vaccine in 2009 and the health of their children in their first five years.

According to estimates, only about 20 per cent of pregnant women in Canada get the flu vaccine, largely due to concerns over its possible effects on their unborn children.

"We know that pregnant women and babies are particularly vulnerable to more serious illness if they get the flu," said study co-author Deshayne Fell, an assistant professor of epidemiology at the University of Ottawa and a scientist with the CHEO Research Institute.

"If pregnant women get the flu shot during their pregnancy, it not only protects them, but also protects the young babies during the first several months of life because the antibodies are transferred to the baby," she told CBC Radio's Ottawa Morning.

She said the findings of the study are reassuring and confirms what some other studies have shown.
The study, published in The BMJ, followed 104,249 children born in Ontario between November 2009 and October 2010 until they were five years old.

Of those, the mothers of only 31,295 of those children - about 30 per cent - received the H1N1 vaccine.

Whether the low rate of vaccination in mothers is due to reluctance or poor access to the flu vaccine isn't known.

The study showed no increased risk of cancer, infections, chronic diseases, hospital admissions or death in those children whose mothers received the flu vaccine.

It did find a slightly increased rate of asthma in some of the children, but a lower rate of gastrointestinal infections. It wasn't clear whether either of those were related to the vaccine or an unrelated cause.

Deadly swine flu
In 2009, the World Health Organization declared a global flu pandemic, its first in four decades. More than 400 Canadians died, including a pre-teen girl at an Ottawa hospital.

That year, approximately 64 per cent of pregnant women across Canada received the H1N1 vaccine.

"This is an important decision for pregnant women because if they or their newborn babies get the flu, they generally get sicker than the rest of the population," Fell wrote.

"We hope the knowledge that the flu shot during pregnancy is safe for children in the longer term will lead to more pregnant woman saying yes to the flu shot."


See also: Flu shots while pregnant tied to lower preterm birth risk