Most pregnant women and unborn babies who contract bird flu will die, research shows

Most pregnant women who contract bird flu will die, according to an Australian review of infections that found most unborn babies with the virus also die.

Caused by influenza A viruses, a severe form of bird flu known as highly pathogenic bird flu A (H5N1) is spreading worldwide.

Although this has led to large outbreaks in poultry and wild birds, spillover infections in mammals and human infections are rare and usually limited to people who work in close contact with sick birds and livestock. There is no evidence of transmission between humans.

Human infections have been linked to the outbreak in some parts of the world, including China and the US. Most human cases have been mild, with only one severe case in the US.

An infectious disease researcher at the Murdoch Children’s Research Institute in Melbourne, Dr Rachael Purcell, said that while many people who became infected with bird flu were “completely fine, we wanted to look at what is known about what happens to pregnant women.” ”.

“A pregnant woman’s immune system does not work the same way it did before pregnancy,” Purcell said. “Unvaccinated pregnant women who get other viruses, such as Covid-19 or seasonal flu, often get sicker than non-pregnant women, but we didn’t really know much about what happens to women with bird flu.”

Purcell and her colleagues examined more than 1,500 research papers to identify confirmed cases of bird flu in pregnant women. They found 30 such cases in China, Vietnam, Cambodia and the US linked to different strains and outbreaks.

The study, published in Emerging Infectious Diseases, found that 90% of women infected with bird flu during pregnancy died, and almost all of their babies (87%) died with it. Of the babies who survived, most were born prematurely.

“What it tells us is that, although the risk of bird flu becoming the next human pandemic is thought to be low, it is very important to think about vulnerable populations and how we can protect them and include them in vaccination programmes” , Purcell said.

“Despite being a high-risk population, pregnant women are often excluded from vaccine trials, from priority access to therapies, and experience delayed access to public health vaccination programs.”

There are no specific vaccines for bird flu in humans, although trial vaccines have been developed in some countries to prepare for pandemics. But these vaccines are not recommended for pregnant women due to a lack of safety data.

“That’s one of the challenges we often have with vaccines, because it’s considered unsafe to test them in pregnant women,” Purcell said. “I think as we move forward we need to think about how we get data on pregnant women.

“When women participate in vaccine safety studies, those women sometimes become pregnant unintentionally, and there is an opportunity to ethically investigate what happens to those women.”

An infectious disease specialist at the Australian National University, Associate Professor Sanjaya Senanayake, said while the size of the study group was small, it represented the fact that most human cases of bird flu are still linked directly or closely contact with poultry, meaning pregnant women are less likely to be exposed.

“If continued human-to-human transmission occurs with further mutations of the virus, that will of course change.”

He added that most of these pregnant women in the study were from developing countries.

“While this is still relevant to a future avian flu pandemic, we cannot necessarily generalize such serious consequences to the developed world with better-funded healthcare institutions,” he said.

Despite these limitations, Senanyake said the study’s findings were “probably real.”

“We know that pregnant women are more susceptible to serious consequences of respiratory infections,” he said.

In October the Australian government announced a sum of $95 million investments in preparation for bird flu. Australia is the only continent that remains free of the deadliest bird flu strain.