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Research reveals importance of whooping cough, flu vaccines for pregnant women

News story

2017 has been Australia’s worst flu season on record, with infants, children and the elderly the most vulnerable to the influenza virus. According to Dr Annette Regan, whose award-winning research focuses on maternal child health, it’s critical for pregnant women to get the flu vaccine and pertussis (whooping cough) vaccine to protect themselves and their unborn children from potentially fatal illnesses, a practice known as ‘maternal immunisation’.

Baby crying

Whooping cough and flu vaccines are free for pregnant women.

The health impacts of influenza and whooping cough are often underestimated, however both viruses can cause debilitating complications, or even death, in vulnerable populations. Vaccinating a pregnant woman against the viruses helps to protect both the mother and her unborn child. The mother will develop antibodies in response to the vaccines, which protect her from infection, and she will transfer these antibodies to her baby via her placenta. Her baby is then protected until s/he is old enough to be immunised. This protection has been described as the ‘ultimate birthday gift’ from a mother to her child.

“When pregnant your immune system is slightly depressed, so if you get an infection it tends to be much more severe and that is very likely to impact on the unborn baby,” says Regan.

“Pregnant women and their infants are at high risk of serious complications from respiratory infections like influenza. For this reason, influenza and pertussis vaccines are currently recommended during every pregnancy.

“Influenza vaccines can be given at any time during pregnancy, and pertussis vaccine is given between 28 and 32 weeks of pregnancy. These vaccines not only protect the mother against infection, but they also prevent serious infections in their infants in the first months of life.”

Maternal vaccination can prevent babies from becoming fatally ill.

Perhaps one of the most high-profile victims of whooping cough is Perth-born baby Riley Hughes. In 2015, at three weeks of age, Riley contracted what appeared to be a cold, but was in fact whooping cough. Riley was quickly hospitalised at Princess Margaret Hospital, but developed pneumonia and, despite treatment, tragically died at four weeks of age.

Two days after Riley’s death, the Western Australian State Government launched a program for pregnant women to access free pertussis booster shots in their third trimester of pregnancy. (Free booster shots are now available for pregnant women in all Australian states and territories, as are flu vaccines.) Riley’s parents, Catherine and Greg Hughes, went on to establish the Immunisation Foundation of Australia, and campaign and advocate for the importance of vaccines for pregnant women and the National Immunisation Program Schedule for infants and children.

Why don’t pregnant women vaccinate?

Despite the availability of free flu and whooping cough vaccines for pregnant women, and the documented safety of these vaccines, the biggest barrier to maternal vaccination is a lack of guidance from treating healthcare professionals.

“By far the biggest factor influencing whether a woman will get vaccinated during pregnancy or not, is whether her healthcare provider recommends it to her. Nearly 80 per cent of women say they would be vaccinated if their provider had recommended it to them,” says Regan.

“There is also sometimes a perception that vaccination is not necessary, as women are not always aware of the severity of these diseases …Women also cite concerns about the safety of the vaccine to their baby, and possible side effects, as a reason why they choose not to be vaccinated.”

The biggest barrier to maternal vaccination is a lack of guidance from treating healthcare professionals.

Vaccines can be a fraught topic amongst some members of the community, who believe vaccinations can cause health issues, or developmental differences, such as Autism Spectrum Disorder, in infants or children. There are no credible studies to support the idea that vaccinations can cause health issues or developmental differences in infants and young children, and vaccines are known to be protective of both the mother and baby’s health, as Regan’s research demonstrates.

“There are unfortunately some anti-vaccine groups who believe that vaccination during pregnancy is not safe and is associated with birth defects, like microcephaly. This is simply not true, as there have been numerous studies showing that both influenza and pertussis vaccines are safe to mothers and their infants,” Regan says.

“In fact, some studies have shown babies may be healthier if born to vaccinated mothers … one of my PhD studies showed that influenza vaccination during pregnancy may reduce the risk of stillbirth.”

Regan’s PhD study, Seasonal Trivalent Influenza Vaccination During Pregnancy and the Incidence of Stillbirth: Population-Based Retrospective Cohort Study, which combined data sources from 60,000 births in Western Australia between 2012 and 2013, showed that pregnant women who had a flu vaccine had half the risk of stillbirth compared to unvaccinated women. The study garnered national attention, and resulted in an increase in maternal immunisation.

Dr Regan accepting Aileen Plant Memorial Prize in Infectious Disease Epidemiology.

Dr Regan accepts the Aileen Plant Memorial Prize in Infectious Disease Epidemiology for her PhD study.

“The results received a lot of media attention, and were publicized through social media. Several women in parenting blogs like Mama Mia and on the Light for Riley page left comments stating they had booked their influenza vaccine because they heard of the study. Given less than two-thirds of women receive an influenza vaccine each year, encouraging more women to get vaccinated is a fantastic result,” she says.

Regan was awarded the prestigious Aileen Plant Memorial Prize in Infectious Disease Epidemiology in 2017 for her PhD research.

One eye on the future

Up until 2015, when Riley Hughes’ death proved a catalyst for maternal vaccinations, pregnant women did not widely receive either flu or whooping cough vaccines, and there is limited data on how these vaccinations impact children’s health in the long term. Regan, in partnership with a Canadian colleague, Associate Professor Deshayne Fell, University of Ottawa, is currently researching this area.

“Although maternal vaccination is not a new idea by any means, until 2015, relatively few pregnant women received these vaccines. As a result, there is little known about the long-term health effects on children,” Regan says.

“Dr Fell and myself are starting a study which will look at the long-term health effects of influenza vaccines and pertussis vaccines given during pregnancy on children in Australia and Canada. This area is pretty exciting, as so few studies currently exist.”

In addition to the recommended flu and whooping cough vaccines, more vaccines for pregnant women are currently being developed, including a vaccine for respiratory syncytial virus, a common respiratory virus, which can cause bronchiolitis and pneumonia in infants. Regan is currently researching the impact of the virus on pregnant women, and the results of her work will inform decisions about the value of the vaccine, or otherwise, for pregnant women.

“I’m currently doing some work with an international network of researchers to identify the clinical importance of respiratory syncytial virus infection during pregnancy. This information will be important for determining whether there is any value of these vaccines for pregnant women in addition to their infants,” she says.

“Public health research offers the opportunity to evaluate and inform policies and interventions, which can make a difference in everyday people’s lives. I most enjoy that the questions my research helps to answer will ultimately be used by prevention programs to promote healthier lives.”

About the researcher

Dr Annette Regan is a perinatal and infectious disease epidemiologist in the School of Public Health at Curtin University. She completed her PhD at the University of Western Australia in 2016, which examined the health effects of maternal immunisation. She has previously worked as an epidemiologist for public health government organisations, including the Department of Health Western Australia and the US Centers for Disease Control and Prevention.

She is originally from Atlanta, Georgia and moved to Perth with her husband and cat in 2011.

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