Since the 2009 epidemic with influenza A/H 1N1 it has generally been advised that pregnant women constitute an “at risk” group that should be vaccinated. In a study by Pasternak and colleagues and the subject of an editorial in the BMJ this week – evidence is presented that give reassurance regarding the safety of this approach. Certainly experience with A/H 1N1 showed that infected women were more likely to become very unwell. Follow up studies also showed poorer perinatal outcomes for the babies of these mothers. The paper by Pasternak suggests vaccinated women have a lower risk of fetal loss and that the use of the vaccine including the use of adjuvants and thiomersal in the vaccine – which have both been issues that have concerned people. This is encouraging. The paper does not answer all the questions. The study excluded pregnancies less than 7 weeks gestation and included few women who were vaccinated in the first trimester of pregnancy. The fact that in the cohort of women studied only 13% had been vaccinated is also a weakness. Nevertheless the paper adds important information to support the vaccination of women in pregnancy.
One of the reasons behind the uptake of vaccine is medical staff not offering the vaccine. This needs to be addressed. The reason women turn down the vaccine more often is due to concerns about damage to their baby – which is entirely understandable. The new information provided by Pasternak will hopefully reassure people over this point. There still appears to be a need to look more closely at outcome following vaccination in the first trimester of pregnancy – however in view of the relatively high prevalence of miscarriage this is a difficult study to carry out.
