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The H1N1 Vaccine and Pregnant Women

The National Institute of Allergy and Infectious Diseases (NIAID) announced in September that it was preparing to conduct a clinical trial of the H1N1 influenza vaccine involving pregnant women. This is welcome news since pregnant women have been identified as a priority group for receiving the vaccine in the United States and in Canada.

The NIAID trial will be completed in July 2010, well after many pregnant women will have been vaccinated, but it appears that the trial will generate some safety and immunogenicity data prior to the beginning of the mass vaccination campaigns planned in the United States and Canada. Other clinical trials studying the safety and efficacy of the H1N1 vaccine have excluded pregnant women altogether.

The vaccine manufacturers in particular seem disinclined to study the effects of their product on this population, even though millions of pregnant women will receive the vaccine because they have a higher risk of serious complications when infected with H1N1. GlaxoSmithKine, for example, is conducting clinical trials of its “adjuvanted” H1N1 vaccine (which contains a substance that boosts the vaccine’s potency) in children and adults, excluding pregnant women. In Canada where the adjuvanted vaccine will be offered, pregnant women will generally be given the vaccine without the adjuvant, since there is insufficient data on the safety of the vaccine adjuvant in pregnant women.

Public health authorities have made the assumption that the nonadjuvanted H1N1 vaccine is safe for pregnant women because seasonal flu vaccines have a good safety track record in pregnancy, and the H1N1 vaccine is produced in the same way as the seasonal flu vaccine. Nonetheless, the H1N1 vaccine is new, and clinical trials involving all populations receiving the vaccine are warranted.

Just as with other drugs, vaccine research involving pregnant participants is a taboo. Underlying this taboo is a fear that research in pregnancy will expose fetuses to harm. Drug companies fear lawsuits that could arise if something goes wrong in a clinical trial and their product is blamed. Bad outcomes such as miscarriage are relatively common in pregnancy, and in a clinical trial a bad pregnancy outcome might lead to costly litigation even if the drug or vaccine being tested was not the cause.

But this taboo is harmful to women, and it is counterproductive to furthering the health of fetuses and infants. In the U.S. and Canada there are only a handful of drugs approved for use in pregnancy. Nonetheless, a majority of pregnant women use more than four medications. Many of these drugs are essentially being prescribed and taken blindly.

In articles published last year in the International Journal of Feminist Approaches to Bioethics and the Hastings Center Report, Anne Drapkin Lyerly, Margaret Olivia Little and Ruth Faden outline four reasons for pursuing the goal of including pregnant women in safe clinical research.

1.      The effective medical treatment of pregnant women depends on creating an evidence-base for their treatment.

2.      Fetal safety would be more securely safeguarded if there was research evidence on the effects of all those drugs taken in pregnancy.

3.      The reluctance to prescribe and use medications in pregnancy can also result in undertreatment, which can negatively affect the health of the pregnant woman and fetus.

4.      Some clinical trials end up benefiting research participants. The exclusion of pregnant women denies them the chance to realize these benefits.

When it comes to vaccine research, there is an additional reason to include pregnant women. When pregnant women are immunized, some vaccines offer the prospect of conveying immunity to serious infectious diseases to the infant after birth, because the mother’s immunity may transfer across the placenta. Direct vaccination for many diseases is not possible in the first months of life, so maternal vaccination could be a strategy for protecting young infants from diseases to which they would otherwise have no immunity. The reluctance to conduct maternal immunization research is a significant lost opportunity.

The fears associated with conducting research involving pregnant women can be overcome, just as the fears associated with including nonpregnant women and children in clinical research were overcome. Research with all of these groups can be conducted safely. The potential for a public health crisis brought by the H1N1 pandemic has made some realize the risks of failing to conduct research involving pregnant women. It shouldn’t take a crisis to provoke this realization.

Chris Kaposy, an assistant professor of health ethics at Memorial University of Newfoundland in Canada, is a member of the Canadian Center for Vaccinology.

Published on: October 6, 2009
Published in: Public Health

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