by Sam Halabi
The CDC announced today that the number of pregnant women in the U.S. infected with the Zika virus has tripled from 48 to 157. The escalation is a reminder of how difficult a public health emergency Zika will be to address given the complex nature of its victims. In my last post, I explained how a Zika vaccine (and vaccines in general) face numerous regulatory obstacles when developed for diseases for which inoculation during pregnancy is the most promising intervention. In this post, I explain why addressing those obstacles is such a significant public health issue.
There are movements toward greater safety evaluation in this area and clinical trials are now underway for some recommended maternal vaccines like influenza and pertussis. But overall there is a lack of standardization for definitions of outcomes as well as ways to measure outcomes. This lack of standardization prevents the generalizability of safety data and extrapolating conclusions from more than one data set. Moreover, the ability to assess risk versus benefit relies on background rates of certain risks relevant to pregnancy like first trimester miscarriage. Without robust data as to these baselines, clinical trials involving pregnant women will not be able to adequately convey risk and benefit. With concerted effort and a willingness to have a conversation about the benefits of maternal immunization, at least some of the tremendous gains realized in the context of childhood immunization might be extended.