Pregnant Women's Perceptions of Risks and Benefits when Considering Participation in Vaccine Trials

"Women's views on participation in Zika Virus vaccine trials offer important lessons for future vaccine development in other disease contexts, including the current global COVID-19 pandemic."

There is consensus around the need to include pregnant women in vaccine development trials, including those that are planned or ongoing for infectious disease outbreaks such as COVID-19 and Zika. This study sought to understand pregnant women's motivations for participating in vaccine trials, their perceptions of the risks and benefits of such research participation, and their decision-making processes.

In response to the 2015-16 North and South American Zika Virus epidemic, the researchers examined pregnant women's willingness to participate in a variety of hypothetical Zika Virus vaccine trials. As part of a mixed-methods study involving 141 participants, they conducted in-depth interviews from May 2017 to August 2017 with 13 women receiving prenatal care at a university hospital in the United States (US). During the interview, women were asked whether they would participate in 4 hypothetical Zika virus vaccine trials (see Figure 1 in the paper). The scenarios were designed to present different levels of vaccine risk for participants, and they reflected an effort to communicate scientific information in an accessible, concise manner.

Acceptance of participation in at least one scenario was common, with only one woman declining all 4 scenarios (see Table 2 in the paper). Interview data demonstrate the complex and interconnected factors that can influence decision-making in pregnancy and decisions about trial participation and reveal that nuanced risk-benefit calculations may contribute to final participation decisions. More specifically, 3 broad themes characterised women's responses to trial scenarios; they are illustrated in the paper with quotations:

• Evidence - The women highly valued evidence in general, and pointed to it as a primary motivator of acceptance or decline of participation. For some, the fact that the vaccine was shown to be safe in pregnant animals and non-pregnant humans was salient; for others, the lack of evidence specific to pregnant women was more significant.
  • Implications for policy and practice: The existence of and communication about data may foster successful design and recruitment of participants. Different types and amounts of data may importantly influence women's views about clinical trial participation during pregnancy. "The high value women place on human pregnancy data when deciding about participation points not only to the importance of designing vaccine trials to specifically address the health interests of pregnant women, but also to conducting robust follow-up on women inadvertently vaccinated in the periconception period during vaccine trials or rollouts, and to making a carefully contextualized analysis of these data available in a timely manner."
  • Implications for research: Collecting pregnancy-specific evidence is a way of respecting pregnant women's motivation to participate in vaccine trials.
• Risk - The majority of women said their concern was predominantly risk of harm to the fetus or baby, and not to themselves. Four primary sources women attributed risk to were: the vaccine, the virus, pregnancy, and the unknown.
  • Implications for policy and practice: In pregnancy, risk perception can be deeply subjective and value laden. Thus: "Women, along with their providers, often need to carefully weigh the relative risks and benefits of intervention and non-intervention, which likely differ between clinical and research settings, as well as non-epidemic and epidemic contexts."
  • Implications for research: Women should be provided information, including as part of consent processes, that allows them to make risk benefit calculations that are complex, personal, and values-driven, within pre-approved parameters determined by ethics committees.
• Trust - In general, women in this sample expressed trust in doctors and in vaccines more broadly. Some women emphasised they would trust their doctors' opinion when making the decision; however, one woman said a doctor recommendation would inform but ultimately not change her reticence toward trial participation. Another indicated she would talk to God when making the decision and trust in her religion to guide her choice. One woman noted her concerns, driven by public hesitance around vaccines, particularly in the face of reports of negative news commentary. Several women described a lack of trust related to government recommendations about vaccine trial participation. Others expressed altruistic motivations and the spoke of the importance of evidence in pregnancy.
• Implications for policy and practice: The results reinforce the importance of clear and transparent communication around vaccines and pregnancy, as well as the fact that it is critical to establish vaccine safety with pregnancy-specific evidence to support recommendations of use in pregnancy.
• Implications for research: In order to facilitate trust and prevent vaccine hesitancy, researchers are advised to get ahead of the curve by gathering and communicating robust evidence.

In conclusion: "As the needs of pregnant women are increasingly addressed in vaccine development efforts to combat emerging epidemic and pandemic threats, these lessons may help the research agenda be more responsive to the priorities of a population it seeks to protect."