Acceptability of a Hypothetical Zika Vaccine among Women from Colombia and Spain Exposed to ZIKV: A Qualitative Study

"Studies on the acceptability of vaccines for pregnant women are critical for vaccine investment, demand strategies, effective implementation, messaging strategies and modes of communication..."

Outbreaks such as cholera, Ebola, and Zika have highlighted the need to understand the social pathways of disease transmission and barriers to health-seeking behaviour. Intense media attention, as has been generated by the Zika virus (ZIKV) epidemic, can boost public concern about the disease and increase people's likelihood to refuse vaccination. Using a qualitative research methodology based on phenomenology and grounded theory, this study aimed to understand perceptions, views, and attitudes about a hypothetical ZIKV vaccine in 2 different contexts: (i) migrant women from Central and South America living in Spain, where there is no local transmission, who travelled to their countries of origin and were diagnosed with ZIKV infection during pregnancy, and healthcare professionals who looked after these women; and (ii) women living in Colombia who delivered a baby with microcephaly during the ZIKV epidemic.

Specifically, in Spain, the study was conducted between September 2018 and February 2020 among 17 women who had been diagnosed with ZIKV infection (confirmed or probable cases) during pregnancy, and 7 female healthcare professionals who assisted them. In Colombia, the study was performed between April and July 2019 among participants from a study conducted on infants with microcephaly in rural and peri-urban areas in Córdoba and Sucre Departments, born during the ZIKV epidemic. They included 7 women who had delivered an infant with microcephaly, as well as one grandmother and main caregiver of a child with microcephaly.

Selected results, which are shared in the report using quotations from the in-depth interviews (IDIs), paired interviews (PIs), and semi-structured interviews (SSIs), include:

• All participants were aware of the preventative purposes of vaccines and recognised their utility to avoid disease. Women in both sites expressed that everybody should be vaccinated, not only pregnant women. Reasons for this statement included: the protection conferred by herd immunity; the fact that ZIKV can be transmitted by sexual contact; and because "mosquitos are everywhere". One of the participants in a PI in Spain mentioned that in their countries of origin, they do not have "anti-vaccine groups like in Europe".
• Almost all women expressed their willingness to be vaccinated with a hypothetical ZIKV vaccine, as long as it is recommended by their healthcare provider. The main reasons for accepting a hypothetical ZIKV vaccine are presented in Table 2 of the paper. Healthcare professionals explained that pregnant women usually are fearful about receiving vaccines during gestation, but that their acceptability depends on factors such as perception of risk, educational level and understanding of the benefits, and how healthcare professionals provide information.
• In Spain, barriers identified by participants to accept vaccination, or circumstances in which women would hesitate before accepting, included being pregnant or breastfeeding at the time of vaccine administration, due to fear and concerns about the safety of the vaccine and its impact on the health of the fetus and the baby. In Colombia, barriers to accept vaccination included the decision, in some women, of not getting pregnant again to avoid the suffering related to ZIKV risk (consequently no need for a vaccine) and the vaccine not being included in the health system's routine care or not being given for free. A key determinant to accept vaccination would be to be sure that the vaccine would not cause any damage in their pregnancy or their child's health.
• Most women declared they would not be comfortable participating in a clinical trial due to concerns about the effect of the vaccine on children's health, possible adverse effects following immunisation (AEFIs), and fear and uncertainty about vaccine safety. Those women said they could reconsider trial participation in order to help other women not to go through their same situation. Healthcare professionals also expressed hesitancy about women participating in clinical trials.

One of the notable findings from this study is that the majority of participants intended to receive a ZIKV vaccine. This may be related to an increased perception of risk and severity as a result of the fact that most of the study population had suffered through infection or lived in a highly endemic and severely affected area. The health belief model (HBM) proposes that individual behaviour is directly shaped by perceptions of risk, which are linked to the sources of information they come from. Consequently, people concerned enough about a disease are probably more likely to adopt health behaviours than others. In general, women were not looking for a protective effect for themselves, but for their babies, since they perceived that ZIKV cannot harm non-pregnant people.

Another finding with possible implications for communicators is the importance of recommendations from healthcare workers. "Frequent misinformation about vaccines in the media make it even more important for healthcare professionals to provide accurate information to their patients in order to increase vaccine acceptability. Studies have shown that when information provided by healthcare professionals is insufficient, people might investigate other sources that may contain misleading information, or information that may be misinterpreted..."

As part of this study, "insights around ZIKV were obtained by women who were affected directly by ZIKV, and who faced the challenges of ZIKV from the beginning of the epidemic in 2015 in different ways. Their views provide us with an excellent image that could influence current health campaigns and communication strategies....The study highlights that for ZIKV vaccine acceptance, messages during vaccine delivery need to address the benefits associated with vaccination and the risks avoided, while emphasizing the safety of the vaccine for the fetus and infant, and compatibility with breastfeeding. Lastly, the engagement of healthcare professionals for effective information and communication about potential ZIKV vaccines is a key element for successful implementation."