NEWS FOCUS:Mothers-to-be have been identified as an 'at risk' group in the swine flu alert – but just how great are the dangers to women and their unborn children?, writes KITTY HOLLAND
PREGNANT WOMEN – of which there are record numbers in Ireland, according to last week’s CSO figures – have been identified as one of the most “at risk” groups of developing serious problems on contracting swine flu.
The HSE says pregnant women will be among the priority groups for vaccination when the vaccine becomes available sometime next month.
Not only are they at greater risk of contracting the virus – because their immune systems are suppressed – but they are also in danger of developing severe and even fatal complications because their respiratory systems are increasingly compromised as pregnancy progresses.
This can lead to problems for their own health but also, particularly in the first trimester, to spontaneous miscarriage due to infection in some cases.
In the United States, where they make up 1 per cent of the population, pregnant women have accounted for 6 per cent of H1N1 cases and a disproportionate number of cases with severe complications. There have been a number of deaths among otherwise healthy, pregnant women.
Concerns are being voiced, however, about the safety of not only the vaccine but also of the anti-virals – Tamiflu and Relenza – which will be used to treat people who develop swine flu.
Pregnant women are, of course, a group apart. Unlike other priority groups – people with chronic heart or lung disease, diabetes or whose immunity is otherwise compromised – they have more than themselves to think about.
Statements from the manufacturers of the vaccine and the medications used to treat swine flu are not wholly reassuring for any mother-to-be concerned about the welfare of her unborn child.
Even the messages about the impact of the H1N1 flu on pregnant women are mixed.
Most, like Dr Chris Fitzpatrick, Master of the Coombe Women and Infants University Hospital, say reassuringly that although pregnant women are at additional risk of complications from the H1N1 virus, “it is very important to emphasise that in the majority of instances the infection will not give rise to adverse complications for either the mother or baby”.
But then there are others, like Dr Anthony Fauci, director of the US Institute of Allergy and Infectious Diseases, which is overseeing the development of a vaccine in the US, who said last month: “It is vitally important that pregnant women take very seriously any illnesses or threats to their respiratory system they get during this flu season.”
The time of greatest risk for the mother, according to Dr Nahoko Shindo, medical officer with the World Health Organisation (WHO), is her third trimester, when the respiratory system is under the greatest pressure.
For her unborn baby, however, this is the time of least risk as it “has finished all the critical development and there is very little risk of deformity”.
“On the contrary, the first trimester is the most sensitive period for the foetus in terms of teratogenesis [deformity] and natural abortion due to infection.”
She said this was the period in pregnancy when “some clinicians do not want to risk themselves by providing anti-virals”.
People were invited to submit questions to a live webcast in the last fortnight, hosted by the US Department of Health and Human Sciences, on swine flu and pregnancy. Question after question came in about the safety for the unborn, and for very young children, of the vaccine and the anti-virals.
The message all experts were keen to get out was that all were safe and there was “nothing really to worry about”. They all conceded though there had been no clinical trials on pregnant women of any of them, though trials of the vaccine on pregnant women would be getting under way in the US.
As a spokeswoman for Roche Pharmaceuticals, Ireland, manufacturer of Tamiflu, pointed out, few clinical trials ever take place on pregnant women “as it’s thought too dangerous for an unborn baby”.
“As a result, we do not have sufficient research data available which studies the behaviour of Tamiflu in pregnant women. We do know that animal studies don’t indicate direct or indirect harmful effects with respect to pregnancy, foetal or postnatal development.”
She said Tamiflu was not licensed for use in pregnant women, “so we are unable to issue guidance as to whether or not it can be used for the treatment of the H1N1 2009 virus in this group”.
However, she went on, the consensual advice from such bodies as the WHO, the US Centre for Disease Control and the European Medicines Agency was that case-by-case judgments should be made by individual clinicians and it could be used “in circumstances where the potential benefit to the mother outweighs the potential risk to the foetus”.
Similarly, a spokeswoman for GlaxoSmithKline, maker of Relenza, said its use during pregnancy had “not been established”. Because of its unknown impact on the foetus, “Relenza should only be used if the potential benefit outweighs the potential risk to the foetus”.
Most Irish and international healthcare professionals, however, say both are safe to use during pregnancy, and no serious adverse effects have been reported where pregnant women have used these.
Regarding the vaccine, experts are pointing to the fact that the normal seasonal flu vaccine – which is very similar to the H1N1 vaccine – has been administered for decades to pregnant women without incident.
Dr Fauci, in the recent live webcast, described any risk from the vaccine to pregnant women as “essentially immeasurable”.
“You should never say there is no risk at all, but if you look at the normal risks in life this is a very, very small risk.”
Of interest to Irish mothers will be his reassurance to American women that they will get a version of the vaccine without the controversial component, Thimerosal, which has been controversially linked to autism and brain development disorders.
A mercury-based compound, it is used as a preservative in vaccines, but since 2000 has been all but banned in the US for use in vaccines for pregnant mothers and young children.
The HSE has no plans to provide a Thimerosal-free version here, a spokesman confirmed last week. He pointed to the scientific consensus, from both the WHO and the US Centre for Disease Control, that Thimerosal was safe for use in vaccines for pregnant women and children.
“The vaccine will be administered to everybody including pregnant women on the basis of informed consent,” he said.
“Pregnant women have a four-fold increased risk of being admitted to hospital if they contract swine flu. The pandemic H1N1 vaccine is currently being tested and we expect it will be licensed by the European Medicines Agency in October,” the HSE said.
Dr Fauci said scientific data suggested there was no safety issue with the compound.
“But people do still feel concerned. We want to alleviate that concern. We try to make the vaccines Thimerosal-free for the children and for pregnant women,” he said, adding that Thimerosal-free formulations would be directed to US mothers and children.