We describe a maternal vaccination rate of 75.9% for pertussis and 34.5% for influenza. This maternal pertussis vaccination coverage in Israel is comparable to that reported in other countries (for example: England –70-75 %16 , United States - 54.4%12 ) but still falls short of target rates. Influenza coverage, on the other hand, is far from satisfactory even when compared to coverage in other countries (for example: United States - 49.1%12 , Belgium - 45%17 ), despite comparable recommendation rates by primary caregivers, found to be a strong predictor of maternal acceptance. In a study published by the Center for Disease Control, 81.0% received recommendation for influenza vaccine resulting in a 49.1% vaccination rate12, compared to 77.3% who reported receiving a recommendation in our study resulting in only 34.5% vaccination. This implies that providing vaccine recommendations as a stand-alone strategy is not enough. This observation may in part be due to a difference in perception of prevalence or severity of these diseases. These results highlight the need for health authorities to implement strategies to actively increase uptake of these vaccines, with an emphasis on influenza.
We report here several reasons for declining maternal vaccinations. Our results point out that 24% of pregnant women did not receive the DTaP vaccine primarily because they were uninformed regarding vaccine recommendation and benefits, information that could have been provided by practitioners. Moreover, concerns about safety played a role in reducing uptake in 39% of women who did not vaccinate (including concerns about side effects to themselves and potential harm to their fetus). As for influenza, the reasons were quite different as 28% declined the vaccine due to the belief that influenza vaccine is not effective and only 18% were uninformed of vaccination recommendations. Safety concerns were still an issue as 29% deferred for these reasons. Emphasis of vaccine recommendation is apparently crucial and should be an important first step in any program to increase vaccine uptake in this population. We suggest that the protective effects and overall efficacy and safety should be actively presented to patients. These results largely reflect current data in numerous studies concluding that knowledge concerning vaccine recommendations, safety and efficacy have a large impact on maternal uptake12,15 5
Our results highlight multiple determinants influencing vaccine uptake. As previously reported by others, higher education and vaccine recommendation by the provider were predictors of vaccination. Prior children had an incremental negative effect on vaccine uptake - the more children at home, the larger the proportion of unvaccinated mothers. These findings may be an indirect reflection of economic status, a well-known determinant not directly assessed in this study. An alternative explanation may be the fact that these vaccines are a relatively recent addition to the health recommendations in pregnancy and mothers who have been through multiple pregnancies may be uninformed, relying on previous pregnancies to decide what procedures are necessary. This emphasizes the important role of the healthcare provider, even in highly experienced patients.
The HMO had an impact on vaccine uptake suggesting a difference in organizational procedures to promote vaccinations. Israel has four public HMOs that every citizen can chose freely to belong to. Our sample largely reflects the national distribution of membership between these providers, albeit Maccabi is slightly over-represented in this study. The smaller providers were merged into a single reference group for statistical measures. Regarding pertussis, 'Maccabi' stood out with a remarkable 86.8% coverage. In contrast, Influenza coverage was highest by members of the 'Meuhedet' group. This discrepancy may hint that different policies of the healthcare-providing organization can influence vaccine uptake, urging local officials to investigate the differences between HMOs vaccination publicity efforts and increase their efforts to promote uptake of all recommended vaccines.
Lastly, we introduce a new variable affecting vaccine uptake - season of pregnancy/delivery. We found a significant difference in vaccine uptake for both pertussis and influenza, depending on season. Those who were in late pregnancy or gave birth during the influenza season were more likely to vaccinate than those pregnant during the late influenza season. The difference in influenza uptake is not surprising, as women who approach their second or third trimester in late influenza season may be inclined to believe the danger of contracting Influenza has passed. However, we were surprised that the same trend was found in the pertussis vaccine uptake, even though the recommendation is not season dependent. The linkage between the vaccinations should make providers emphasize the importance of the pertussis vaccine during the warm months. Another concern is that many surveys regarding pertussis coverage are collected in parallel to influenza uptake, meaning that studies performed during peak influenza season are potentially causing over-estimations of yearly pertussis uptake.
Our observation regarding exposure to social media and its impact upon vaccine acceptance should be taken into consideration by regulators and policy makers as well. We showed that in one-fifth (20.9%) of women their decision whether to receive the vaccines was influenced by social media. It is essential that we make sure reliable information is spread through these channels. Furthermore, providers need to inquire about their patients’ sources of information and point them towards reliable sources.
The strengths of this study include a >90% compliance rate, and the institution in which we conducted this study, that is, a tertiary center with >9000 yearly deliveries representing all local ethnic and demographic groups. However, as this was a self-reported questionnaire study, limitations include a possible recall bias and social desirability bias which may have caused overestimation of actual coverage. Another limitation was the language barrier potentially causing some selection bias. However, only 7 out of 320 subjects were excluded from the study due to language barriers, having a minimal influence on the results.