Pertussis vaccination coverage among Australian women prior to childbirth in the cocooning era: a two-hospital, cross-sectional survey, 2010 to 2013

Safety and Clinical Benefits of Adacel® and Adacel®-Polio Vaccination in Pregnancy: A Structured Literature Review

Vaccination in pregnancy using a tetanus toxoid, reduced dose diphtheria toxoid, and reduced dose acellular pertussis (Tdap) vaccine is important for prevention of severe pertussis disease in young infants. The objectives of this systematic literature review were to search for original research studies evaluating the vaccine effectiveness, immunogenicity, and safety of Adacel®/Adacel-Polio® used during pregnancy to prevent pertussis disease in young infants. Medical databases used included EMBASE, BIOSIS Previews, and Chemical Abstracts, with search terms related to pregnancy, vaccines/immunization, safety, pertussis, effectiveness/efficacy, and immune response; other potentially eligible reports were included where applicable. Search results were restricted to literature published from 1 January 1995 to 26 July 2021. A total of 2021 articles and 4 other reports were identified for primary review. A total of 49 publications qualified for inclusion after primary and secondary reviews. Effectiveness studies of Adacel or Adacel-Polio given in pregnancy consistently showed high levels of protection from pertussis disease in the newborn (vaccine effectiveness: 91-93%). In immunogenicity studies, the response in pregnant women was consistent with that of non-pregnant women. Infants of mothers vaccinated with Adacel or Adacel-Polio in pregnancy had higher anti-pertussis antibody levels at birth and at 2 months of age compared to infants born to women vaccinated with comparator vaccines, placebo, or those not vaccinated during pregnancy. There was evidence of a slightly decreased response to primary pertussis vaccination in infants of mothers vaccinated with Adacel or Adacel-Polio, but this was not thought to be clinically significant. In safety studies, Adacel or Adacel-Polio vaccination was well tolerated by pregnant woman and not associated with pregnancy, postpartum, or neonatal complications. In conclusion, Adacel or Adacel-Polio vaccination in pregnancy is highly effective in protecting young infants from pertussis disease, with a favorable safety profile for both pregnant women and their infants.

Socio-psychological determinants of second trimester maternal pertussis vaccination acceptance in the Netherlands

BACKGROUND

A maternal tetanus-diphtheria-and-acellular-pertussis (Tdap) vaccine is offered to all pregnant women in the Netherlands in their second trimester since December 2019. However, former studies solely investigated the socio-psychological factors that influence vaccine acceptance among pregnant women in the third trimester. We identified predicting factors for attitude, intention and acceptance of maternal Tdap vaccination during the second trimester of pregnancy.

METHODS

As part of a large prospective cohort study, women early in pregnancy completed a questionnaire on determinants regarding acceptance of maternal Tdap vaccination between 20 and 24w of gestation. The vaccine was offered after completion of the questionnaire. A random forest model and Receiver Operating Characteristics (ROC) analyses were carried out to identify the factors most predictive for vaccine acceptance on the whole data set, and also in sensitivity analysis on a subset reflecting the annual nationwide 70% vaccination uptake.

RESULTS

Among 1158 participants who were offered a Tdap vaccination between 20 and 24w of gestation, 1098 (94.8%) accepted and 60 (5.2%) rejected the vaccine. Random forest analyses identified intention as most predictive for acceptance, followed by attitude towards vaccination, beliefs regarding safety, risk perception of severity of side effects, moral responsibility, beliefs regarding effectiveness and risk perception of susceptibility of side effects, with a sensitivity of 100% and a specificity of 40%, for which this combination could be improved by the ROC analysis to 82% and 67%, respectively. The sensitivity analysis yielded an order of predictors that generally corresponded with the initial model.

CONCLUSIONS

Intention, attitude, beliefs on safety and effectiveness, risk perception of side effects and moral responsibility were most predictive for maternal Tdap vaccine acceptance during the second trimester of pregnancy, in accordance with studies regarding third trimester vaccination. These should be discussed by healthcare professionals early in pregnancy to provide an informed choice towards vaccine acceptance.

Maternal vaccination against pertussis as part of the national immunization program: a qualitative evaluation among obstetric care providers one year after the implementation in December 2019

BACKGROUND

Immunization of pregnant women with a tetanus-diphtheria-and-acellular-pertussis (Tdap) vaccine is an effective and safe way to protect infants from pertussis before their primary vaccinations. Vaccine uptake among pregnant women is influenced by their care providers' attitudes toward maternal vaccination. This qualitative study aimed to evaluate the implementation of the maternal Tdap vaccination under the National Immunization Program of the Netherlands from the perspective of obstetric care providers.

METHODS

In this qualitative and explorative study, we conducted in-depth interviews by telephone with obstetric care providers who were selected from a pool of respondents (convenience sampling) to a questionnaire in a previous study. The interviews were based on a semi-structured interview guide that covered three aspects of the implementation strategy: providers' overall experience with the implementation of maternal Tdap vaccination in the Netherlands; implementation logistics and counseling, and pregnant women referrals to municipal Youth Healthcare Centers. The interviews were recorded, pseudonymized and transcribed verbatim. Transcripts were analyzed according to the Thematic Analysis approach by two researchers independently in two phases of iterative coding, categorizing, reviewing and redefining until ultimately, emergent themes regarding maternal Tdap vaccination implementation were identified.

RESULTS

Interviews with 11 midwives and 5 OB-GYN physicians yielded 5 major themes regarding the Tdap vaccination implementation strategy: challenges throughout the implementation process, views on maternal Tdap vaccination, general versus tailored counseling, provider responsibilities in vaccine promotion, and impact of materials for information delivery. Participants indicated that to improve provider attitudes toward Tdap vaccination, its implementation requires clear and transparent information about what is entailed, i.e., what is expected from obstetric care providers, how they can obtain information, and when their actions must be initiated. Participants demanded involvement throughout the implementation planning process. They preferred tailored communication with pregnant women over a generalized approach.

CONCLUSION

This study emphasized the importance of involving all relevant healthcare professionals in planning the implementation of maternal Tdap vaccination. Possible barriers perceived by these professionals should be taken into account in order to improve their attitudes toward vaccination, thus to increase uptake among pregnant women.

Models of determinants of COVID-19 vaccine hesitancy in non-pregnant and pregnant population: Review of current literature"

Vaccination has proven to be the most effective tool in controlling the COVID-19 pandemic. While pregnant individuals are considered to be a high-risk population and are more likely to experience adverse effects from COVID-19, vaccination rates among pregnant individuals are significantly lower than in the general population. The Health Belief Model (HBM), Theory of Planned Behavior (TPB), 3C model, 5C model, and 5A model have been used to assess vaccination hesitancy behaviors. In this paper, we review the use of each of these models to address vaccine hesitancy, with a focus on the pregnant population and the COVID-19 vaccine. The HBM, TPB, 3C model, and 5C model have demonstrated great versatility in their ability to evaluate, explain, and modify vaccine hesitancy and behavior. Up to date, the HBM and 3C models appear to be the most effective models to study and address vaccination hesitancy within the pregnant persons.

Pertussis Disease and Antenatal Vaccine Effectiveness in Australian Children

BACKGROUND

Population-level studies of severe pertussis extending beyond infancy are sparse, and none in the context of antenatal vaccination. We compared hospitalized pertussis cases from birth to 15 years of age before and after introduction of antenatal immunization.

METHODS

Active surveillance of laboratory-confirmed pertussis hospitalizations in a national network of pediatric hospitals in Australia January 2012 to June 2019. Impact of maternal vaccination was assessed by vaccine effectiveness (VE) in cases and test-negative controls with <2 months of age and by before-after comparison of age distribution of cases. Among cases eligible for one or more vaccine doses, we examined proportions age-appropriately immunized and with comorbidities by age group.

RESULTS

Among 419 eligible cases, the proportion <2 months of age significantly decreased from 33.1% in 2012 to 2014 compared with 19.6% in 2016 to 2019 when mothers of only 4 of 17 (23.5%) cases <2 months of age had received antenatal vaccination. VE was estimated to be 84.3% (95% CI, 26.1-96.7). Across all years (2012-2019), of 55 cases 4-11 months of age, 21 (38%) had ≥2 vaccine doses, whereas among 155 cases ≥12 months of age, 122 (85.2%) had ≥3 vaccine doses. Prevalence of comorbidities (primarily cardiorespiratory) increased from 5 (2.1%) <6 months of age to 36 (24.2%) ≥12 months of age (P < 0.001), with 6/16 (38%) cases ≥12 months of age who required intensive care having comorbidities.

CONCLUSIONS

Below the age of 12 months, prevention of severe pertussis will be maximized by high maternal antenatal vaccine uptake and timeliness of infant vaccine doses. Despite full immunization, we found children ≥12 months of age accounted for 27% of hospitalizations <15 years, with 24% having comorbities, suggesting new vaccine strategies, such as additional doses or more immunogenic vaccines, require evaluation.

Factors affecting pregnant women's decisions regarding prenatal pertussis vaccination: A decision-making study in the nationwide Prenatal Pertussis Immunization Program in Taiwan

OBJECTIVE

To examine the factors affecting pregnant women's decisions to accept or decline the prenatal pertussis (Tdap) vaccination in Taiwan.

MATERIALS AND METHODS

We conducted a cross-sectional survey, recruiting pregnant women who had received prenatal care from eight maternity hospitals between January and December 2018. We examined the participants' demographic characteristics, perceptions of pertussis disease risk and vaccination effectiveness, beliefs regarding vaccine information, physician recommendation, and other potential factors affecting decision-making regarding prenatal vaccination.

RESULTS

The complete survey response rate among eligible women was 78%. Among the participants, 74% accepted and 26% declined prenatal Tdap vaccination. Most women accepted Tdap during pregnancy because of perceived severity of pertussis in their infants, perceived effectiveness of the prenatal Tdap in preventing neonatal pertussis, and perceived safety of the prenatal Tdap vaccine for the fetus, as well as a provider's recommendation, which was the factor strongly associated with actual Tdap reception. Most of the participants who accepted Tdap vaccination during pregnancy and who believed that the Tdap vaccine could protect their infants from pertussis reported the receiving sufficient information to make an informed decision and trust in the information. By contrast, a large proportion of the participants who declined Tdap and who did not want to experience possible fetal side effects of Tdap reported not getting sufficient information to make an informed decision and a lack of trust in the information.

CONCLUSION

Developing a comprehensive strategy involving government policy, the health care system, public media, health professionals, and pregnant women to launch a successful campaign may improve the nationwide acceptance of the prenatal pertussis vaccination.

Social-psychological determinants of maternal pertussis vaccination acceptance during pregnancy among women in the Netherlands

BACKGROUND

Maternal Pertussis Vaccination (MPV) during pregnancy became part of the National Immunization Program in the Netherlands late 2019. This study aims to identify social-psychological factors associated with MPV acceptance among Dutch women to add to the current understanding of vaccine hesitancy worldwide, and to inform the development of communication and information campaigns about MPV.

METHODS

We conducted a cross-sectional study using an online survey among 611 women (174 pregnant women, 205 women who had given birth in the past two years and 232 women of 20-35 years old). The primary and secondary outcomes were vaccination intention and attitude towards MPV, respectively. Pearson's correlation and regression analyses were used to examine social-psychological and socio-demographic determinants of the outcomes.

RESULTS

Vaccination intention was most explained by attitudes towards MPV, beliefs about safety, moral norm and the belief about the effectiveness of MPV (R² = 0.79). Other factors associated were injunctive norm, anticipated regret of vaccinating, and decisional certainty. Attitudes towards MPV were further explained by descriptive norm, risk perceptions of side effects, and risk perceptions of the baby getting pertussis when not vaccinating, and fear of MPV and of the disease (R² = 0.76). Finally, pregnant women had a significantly lower intention and less positive attitude towards MPV than non-pregnant women.

CONCLUSIONS

Communication about MPV should address the most important determinants of MPV intention and attitude, i.e. beliefs about safety and effectiveness and moral norms. Furthermore, such information may benefit from taking into account affective feelings of pregnant women such as anticipated regret and fear towards MPV. Further research could explore this. The timing of communication about MPV can be important as determinants of MPV acceptance may vary depending on pregnancy status.

Antenatal vaccine uptake: A cross-sectional study investigating factors influencing women's choices in pregnancy

BACKGROUND

Seasonal influenza and pertussis cause significant morbidity and mortality among expectant mothers and infants. Vaccination during the antenatal period is an important public health intervention, minimising rates of maternal, neonatal and infant infection.

AIMS

The primary aim of this project was to establish the rates of antenatal vaccine uptake. Secondly, the study aimed to determine socio-demographic factors significant to vaccine uptake. Thirdly, the project aimed to produce a thematic analysis of the factors affecting vaccination uptake during pregnancy.

MATERIALS AND METHODS

A cross-sectional observational study was conducted among women attending a large maternity hospital, in the western suburbs of Melbourne, for perinatal care. Data were collected via self-completed questionnaires after delivery. Data from the questionnaires were entered into an electronic database, and STATA was used to undertake correlation analysis.

RESULTS

Over a 12-month period 1678 women completed questionnaires and 1305 were eligible for further analysis. The uptake of influenza vaccine was 48.3%, pertussis vaccine uptake was higher, at 82.9%. Uptake of influenza and pertussis vaccines strongly correlated with recommendations from healthcare providers (odds ratios 29.7 and 63.8 respectively). Maternal country of birth, age and parity were significant predictors of vaccine uptake. In thematic analysis, healthcare provider recommendation and the perceived risk of the disease were factors resulting in vaccination.

CONCLUSION

This study determined the rate of antenatal vaccine uptake and significant socio-demographic determinants affecting uptake at a large maternity hospital in metropolitan Melbourne. Ensuring healthcare providers recommend vaccination is likely to improve coverage.

Factors associated with uptake of influenza and pertussis vaccines among pregnant women in South Australia

BACKGROUND

Maternal immunization is an effective strategy to protect pregnant women and their infants from vaccine-preventable diseases. Despite the recommendation of maternal influenza and more recently pertussis immunization in Australia, uptake of these vaccines has been suboptimal. A midwife delivered immunization program for pregnant women at the Women's and Children's Hospital in South Australia commenced in April 2015. Monitoring the uptake of the current funded vaccine programs for pregnant women is limited. The study aimed to estimate maternal vaccine uptake and assess factors associated with influenza and pertussis vaccine uptake among pregnant women.

METHODS

This prospective study was undertaken between November 2014 and July 2016 at the Women's and Children's Hospital. Following consent, demographic details and vaccination history for South Australian pregnant women who attended the antenatal clinic were collected. A standardised self-reported survey was completed during pregnancy with a follow up telephone interview at 8-10 weeks post-delivery.

RESULTS

205 women consented and completed the self-reported survey. Of the 180 pregnant women who completed the study, 76% and 81% received maternal influenza and pertussis vaccines respectively. The adjusted odds of women receiving maternal vaccines during pregnancy were significantly higher for women delivering after the implementation of the midwife delivered program compared with women who delivered babies prior to the program for both pertussis vaccination (AOR 21.17, 95% CI 6.14-72.95; p<0.001) and influenza vaccination (AOR 5.95, 95% CI 2.13-16.61, p<0.001). Women receiving a recommendation from a health care provider and first time mothers were significantly more likely to receive influenza vaccination during pregnancy.

CONCLUSIONS

High uptake of influenza and pertussis vaccines during pregnancy can be attained with health care provider recommendation and inclusion of maternal immunization as part of standard antenatal care. A midwife delivered maternal immunization program is a promising approach to improve maternal vaccine uptake by pregnant women.

Immunization During Pregnancy: Impact on the Infant

Maternal immunization has undergone a paradigm shift in recent years, as women and healthcare providers accept and recognize the benefits of this strategy not only for the pregnant woman but also for the developing fetus and young infant. This article reviews the evidence for active immunization during pregnancy, with an emphasis on perinatal and infant outcomes. Current recommendations for immunization during pregnancy are presented, with particular focus on the routinely recommended vaccines during pregnancy: influenza and Tdap (tetanus, diphtheria, and pertussis). We discuss future research directions, maternal vaccines in development, and considerations for optimizing and advancing this underutilized strategy.

Assessing determinants of the intention to accept a pertussis cocooning vaccination: A survey among Dutch parents

INTRODUCTION

Pertussis cocooning is one of the strategies aiming to prevent the potential harm of pertussis in infants by vaccinating (among others) their parents. Several countries adopted this strategy, but uptake is a problem. Determinants of parental uptake are important in the design of an effective vaccination programme. Therefore, this study aims to assess parents' intention to accept a pertussis cocooning vaccination and its determinants.

METHODS

A 98 item questionnaire was developed based on a theoretical framework, assessing parents' intention to accept a pertussis cocooning vaccination and its personal and psychosocial determinants. In addition, beliefs underlying parents' attitude towards pertussis cocooning vaccination were assessed. Both logistic and linear regression analysis were used to assess univariate and multivariate associations amongst study variables.

RESULTS

Parents returned 282 questionnaires. The majority of the parents (78%) reported a positive intention to accept a pertussis cocooning vaccination. Attitude (OR 6.6, p<.001), anticipated negative affect in response to non acceptance (OR 1.65, p<.001), anticipated negative affect in response to acceptance (OR 0.55, p .040) and decisional uncertainty (OR 0.52, p .002) were significantly associated with intention. General vaccination beliefs (β 0.58, p<.001), moral norm (β 0.22, p<.001), perceived susceptibility of pertussis in children (β 0.10, p.004), and efficacy outcome expectations (β 0.15, p.011) were significant correlates of attitude towards pertussis cocooning vaccination.

CONCLUSION

The parental intention to accept a pertussis cocooning vaccination in this study is rather high. Targeting the identified determinants of parents' acceptance in a pertussis cocooning vaccination programme is crucial to secure that intention is translated into actual vaccination uptake.

Intention to Accept Pertussis Vaccination for Cocooning: A Qualitative Study of the Determinants

Context

Several countries have reported a resurgence of pertussis in the last decades. This puts infants (especially <6 months) at risk of severe complications, because they are too young to be fully protected by vaccination. The global pertussis initiative has proposed pertussis vaccination of young infants’ close contacts, in order to reduce pertussis transmission and the burden of the disease on infants. Our aim is to explore the perceived determinants (barriers and facilitators) of intention to accept vaccination among the possible target groups of pertussis vaccination for cocooning. Consideration of these determinants is necessary to optimise the uptake of the vaccination.

Methods

We conducted 13 focus groups and six individual semi-structured interviews with members of possible target groups for pertussis cocooning (i.e. parents, maternity assistants, midwives, and paediatric nurses) in the Netherlands. Here, both maternal pertussis vaccination as well as pertussis cocooning has not been implemented. The topic list was based on a literature review and a barrier framework. All interviews were transcribed verbatim and two researchers performed thematic content analysis.

Findings

The participants’ risk perception, outcome expectations, general vaccination beliefs, moral norms, opinion of others, perceived autonomy, anticipated regret, decisional uncertainty, and perceived organisational barriers were all factors that influenced the intention to accept pertussis vaccination for cocooning.

Discussion

This study has identified nine perceived determinants that influence the intention to accept pertussis cocooning vaccination. We add the following determinants to the literature: perceived cost-effectiveness (as a concept of outcome expectations), justice (as a concept of moral norms), anticipated regret, and decisional uncertainty. We recommend considering these determinants in vaccination programmes for pertussis cocooning vaccination. Experience, information and trust emerged as predominant themes within these determinants. These themes require particular attention in future research on vaccination acceptance, especially with regard to their role in use and implementation in policy and practice.