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•Feasibility of estimating pertussis vaccination covering using 7 European healthcare databases.•The majority of children were vaccinated at the recommended age of vaccination.•Two estimation methods provided comparable coverage estimates.•Benchmarking using national coverage estimates showed comparable results.•The approached used provided reliable estimates for pertussis vaccination coverage. The Accelerated Development of VAccine beNefit-risk Collaboration in Europe (ADVANCE) is a public-private collaboration aiming to develop and test a system for rapid benefit-risk (B/R) monitoring of vaccines, using existing healthcare databases in Europe. The objective of this paper was to assess the feasibility of using electronic healthcare databases to estimate dose-specific acellular pertussis (aP) and whole cell pertussis (wP) vaccine coverage. Seven electronic healthcare databases in four European countries (Denmark (n = 2), UK (n = 2), Spain (n = 2) and Italy (n = 1)) participated in this study. Children were included from birth and followed up to age six years. Vaccination exposure was obtained from the databases and classified by type (aP or wP), and dose 1, 2 or 3. Coverage was estimated using period prevalence. For the 2006 birth cohort, two estimation methods for pertussis vaccine coverage, period prevalence and cumulative incidence were compared for each database. The majority of the 2,575,576 children included had been vaccinated at the country-specific recommended ages. Overall, the estimated dose 3 coverage was 88–97% in Denmark (birth cohorts from 2003 to 2014), 96–100% in the UK (2003–2014), 95–98% in Spain (2004–2014) and 94% in Italy (2006–2007). The estimated dose 3 coverage per birth cohort in Denmark and the UK differed by 1–6% compared with national estimates, with our estimates mostly higher. The estimated dose 3 coverage in Spain differed by 0–2% with no consistent over- or underestimation. In Italy, the estimates were 3% lower compared with the national estimates. Except for Italy, for which the two coverage estimation methods generated the same results, the estimated cumulative incidence coverages were consistently 1–10% lower than period prevalence estimates. This study showed that it was possible to provide consistent estimates of pertussis immunisation coverage from the electronic healthcare databases included, and that the estimates were comparable with the national estimates.

The effectiveness of maternal immunization in preventing infant pertussis was first demonstrated in England, 1 year after the program using diphtheria–tetanus–5-component acellular pertussis–inactivated polio vaccine (dT5aP-IPV) was introduced in 2012. Vaccine effectiveness against laboratory-confirmed pertussis has been sustained >90% in the 3 years following its introduction, despite changing to another acellular vaccine with different antigen composition. Consistent with this, disease incidence in infants <3 months of age has remained low despite high activity persisting in those aged 1 year and older. Vaccine effectiveness against infant deaths was estimated at 95% (95% confidence interval, 79%–100%). Additional protection from maternal immunization is retained in infants who received their first dose of the primary series. There is no longer evidence of additional protection from maternal vaccination after the third infant dose. Although numbers are small and ongoing assessment is required, there is no evidence of increased risk of disease after primary immunization in infants whose mothers received maternal vaccination.

Vaccination of pregnant women (PW) is an essential public health measure with benefits for both mothers and newborns. Vaccination against seasonal influenza and pertussis have been recommended in Spain for almost a decade; however, the adherence to this recommendation is variable. The objective of this study was to assess pertussis vaccination coverage (PVC) and influenza vaccination coverage (IVC) among PW in the region of Madrid, Spain, and to explore the factors associated with vaccination. We conducted a retrospective cohort study using administrative registries. For PVC 197,984 PW who gave birth between 2019 and 2022 were included in the study. For IVC, 182,014 PW target of the 2018–19 to 2022–23 seasonal influenza campaigns were included. Generalized estimating equations were used to estimate factors associated with vaccination. The global VC in PW was 87.0 % for pertussis and 53.2 % for influenza. A peak was observed coinciding with the start of COVID-19 vaccination. Factors associated with lower probability of being vaccinated were mother born in a foreign country (Pertussis: aOR:0.73 (95 %CI:0.71–0.76); Influenza: aOR:0.71 (95 %CI:0.69–0.73)), enrolment in public healthcare insurance in last stages or after delivery (Pertussis: aOR:0.04 (95 %CI:0.04–0.05); Influenza: aOR:0.09 (95 %CI:0.08–0.11)) and home births (Pertussis: aOR:0.11 (95 %CI:0.08–0.16); Influenza: aOR:0.22 (95 %CI:0.15–0.31)). PW aged between 30 and 39 years old, with full term pregnancies, who live in areas with middle net incomes and have at least one chronic condition with indication for vaccination were more likely to be vaccinated. Significant challenges remain to improve vaccination uptake in PW, particularly concerning influenza. These findings may prove useful to tailor strategies to reach specific subgroups within the PW population. •Vaccination in pregnancy reduces disease burden in women and their infants.•In Madrid, Spain, vaccine coverage is lower for influenza than for whooping cough.•Vaccination uptake has decreased since COVID-19 pandemic.•Foreign, lower-income and adolescent women are less likely to get vaccinated.•Potential inequalities in maternal immunization coverage should be addressed.

•HCPs play an important role in informing pregnant women about maternal vaccinations.•Strategies to increase MPV uptake should not only focus on providing information.•Decrease experienced barriers in pregnant women that are intended to accept the MPV. In December 2019, the maternal pertussis vaccination (MPV) became part of the Dutch National Immunization Program. This study aims to study MPV behavior and associated psychosocial, attitudinal and organizational factors of pertussis vaccination behavior during pregnancy in the Netherlands. We conducted a cross-sectional survey among pregnant women and recent mothers, up to six months post-partum. The primary outcome measure of this study was MPV behavior. Associations between psychosocial, attitudinal and organizational factors and MPV behavior were assessed using univariate and multivariate binary logistic regression analysis. In total 1348 participants filled out the questionnaire, including 1282 (95.1%) MPV acceptors and 66 (4.9%) MPV refusers. The most important factors associated with MPV behavior were: attitude (aOR: 10.19; 95%CI: 4.30–24.16), outcome expectations (aOR: 8.94; 95%CI: 3.60–22.21), omission bias (aOR: 0.11; 95%CI: 0.02–0.59) and physical accessibility (aOR: 7.44; 95%CI: 3.37–16.46). Pregnant women make their decision about the MPV primarily based on attitudinal and psychosocial factors, such as outcome expectations and attitude. A combination and variation of different messages, about the advantages (effectiveness) and disadvantages (side effects) of maternal vaccination, can be used in reaching pregnant women with a positive and negative attitude about the MPV. In addition, strategies to increase MPV uptake should not only focus on providing information, but also decrease experienced practical barriers, such as poor physical accessibility, in people that are intended to receive the MPV but are not getting vaccinated.

Maternal pertussis vaccination during the third trimester of pregnancy was implemented in 2015 in Spain, reaching a national coverage of 84% in 2019. In this ecological study, we investigated whether there was a change in the disease severity for pertussis in infants upon introduction of prenatal pertussis vaccination. We performed a time-trend analysis of infant pertussis hospitalizations during 2005–2019 in Spain using national register data. Annual hospitalization rates per 100,000 population and the mean length of hospitalization were calculated for infants < 3 months of age (target group benefiting from the prenatal vaccination) and a reference group aged 3–11 months. We compared overall rates and annual percent changes of the above variables in both groups for the time period before (2005–2014) and after vaccination introduction (2015–2019), using segmented Poisson regression. During the pre-vaccination period, infants aged 0–2 months had a 5-times higher rate of pertussis hospitalization and spent on average 50 % longer in hospital than the reference group. After the maternal vaccination introduction, the hospitalization rate decreased more rapidly in infants aged 0–2 months than in infants aged 3–11 months: annual reduction of 34 % (95 % CI: 31–38) versus 26 % (95 % CI: 21–31) in the hospitalization rate and 13 % (95 % CI: 11–15) versus 6 % (95 % CI: 2–9) in the mean hospital stay, respectively. In 2019, the mean hospital stay for pertussis was about 4.5 days in both groups. Maternal pertussis vaccination in Spain led to a reduction in disease severity in the target group as compared to older infants, highlighting the need for increased efforts on educating healthcare professionals on the importance of maternal vaccinations.

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. 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. 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. 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.

•Higher DTaP-specific IgG4 levels were observed in aP- versus wP-primed children.•Pertussis priming determines DTaP-specific IgG subclass distribution in childhood.•Low IgG1/IgG4 ratio's may contribute to reduced protection against pertussis. Duration of protection against pertussis is shorter in adolescents who have been immunized with acellular pertussis (aP) in infancy compared with adolescents who received whole-cell pertussis (wP) vaccines in infancy, which is related to immune responses elicited by these priming vaccines. To better understand differences in vaccine induced immunity, we determined pertussis, diphtheria, and tetanus (DTaP) vaccine antigen-specific IgG subclass responses in wP- and aP-primed children before and after two successive DTaP booster vaccinations. Blood samples were collected in a cross-sectional study from wP- or aP-primed children before and 1 month after the pre-school DTaP booster vaccination at age 4 years. Blood samples were collected from two different wP- and aP-primed groups of children before, 1 month and 1 year after an additional pre-adolescent Tdap booster at age 9 years. IgG subclass levels against the antigens included in the DTaP vaccine have been determined with fluorescent-bead-based multiplex immunoassays. At 4 years of age, the IgG4 proportion and concentration for pertussis, diphtheria and tetanus vaccine antigens were significantly higher in aP-primed children compared with wP-primed children. IgG4 concentrations further increased upon the two successive booster vaccinations at 4 and 9 years of age in both wP- and aP-primed children, but remained significantly higher in aP-primed children. The pertussis vaccinations administered in the primary series at infancy determine the vaccine antigen-specific IgG subclass profiles, not only against the pertussis vaccine antigens, but also against the co-administered diphtheria and tetanus vaccine antigens. These profiles did not change after DTaP booster vaccinations later in childhood. The different immune response with high proportions of specific IgG4 in some aP-primed children may contribute to a reduced protection against pertussis. ISRCTN65428640; ISRCTN64117538; NTR4089.

The Accelerated Development of VAccine benefit-risk Collaboration in Europe (ADVANCE), a public-private consortium, implemented and tested a distributed network system for the generation of evidence on the benefits-risks of marketed vaccines in Europe. We tested the system by estimating the incidence rate (IR) of pertussis and pertussis-related complications in children vaccinated with acellular (aP) and whole-cell (wP) pertussis vaccine. Data from seven electronic databases from four countries (Denmark: AUH and SSI, Spain: SIDIAP and BIFAP, UK: THIN and RCGP RSC and Italy: Pedianet) were included in a retrospective cohort analysis. Exposure was defined as any pertussis vaccination (aP or wP). The follow-up time started 14 days after the first dose. Children who had received any pertussis vaccine from January 1990 to December 2015 were included (those who switched type, or had unknown type were excluded). The outcomes of interest were confirmed or suspected pertussis and pertussis-related pneumonia and generalised convulsions within one month of pertussis diagnosis and death within three months of pertussis diagnosis. The cohort comprised 2,886,367 children ≤5 years of age. Data on wP and aP vaccination were available in three and seven databases, respectively. The IRs (per 100,000 person-years) for pertussis varied largely and ranged between 0.15 (95% CI: 0.12; 0.19) and 1.15 (95% CI: 1.07; 1.23), and the trends over time was consistent with those observed from national surveillance databases for confirmed pertussis. The pertussis IRs decreased as the number of wP and aP vaccine doses increased. Pertussis-related complications were rare (89 pneumonia, 7 generalised convulsions and no deaths) and their relative risk (vs. non-pertussis) could not be reliably estimated. The study demonstrated the feasibility of the ADVANCE system to estimate the change in pertussis IRs following pertussis vaccination. Larger sample sizes would provide additional power to compare the risk for complications between children with and without pertussis. The feasibility of vaccine-type specific effectiveness studies may be considered in the future.

Background Healthcare professionals (HCPs) play a significant role in the decision-making process of pregnant women on maternal vaccinations. Whereas a high proportion of HCPs discuss maternal vaccinations with pregnant women, confidence in discussing maternal vaccinations is lacking and HCPs experience inadequate training to discuss maternal vaccinations with pregnant women. Furthermore, different practical barriers might influence the consultation process, such as lack of time. More studies on the barriers, as well as facilitators, to discussing maternal vaccinations is needed and will help us to better understand and support HCPs in discussing maternal vaccinations. Methods This qualitative study involved semi-structured interviews with fourteen HCPs working as midwives or gynaecologists in the Netherlands. An integrated theoretical approach was used to inform data collection and analysis. Thematic analysis was conducted using inductive and deductive approaches. This study followed the COnsolidated criteria for REporting Qualitative research (COREQ) guidelines. Results The thematic analysis of the data pointed to the following five themes of HCP counselling: the consultation process, attitude, perceived norm, perceived control and improvement ideas. Most HCPs follow a similar approach in maternal pertussis vaccination consultations, beginning by assessing clients’ understanding, providing basic information, and addressing questions. However, consultation timing and prioritization vary among HCPs. Challenges in consultations include client requests for clear advice, with HCPs trained to remain neutral, emphasizing client autonomy in decision-making. Most HCPs acknowledge the importance of their consultations in informing pregnant women about maternal pertussis vaccination. Conclusions This study offers a confirmation of the awareness of the pivotal role of HCPs in informing pregnant women about the maternal pertussis vaccination. HCPs stress the importance of neutral counselling, enabling pregnant women to make well-informed decisions independently. Because of upcoming vaccine hesitancy nowadays, HCPs must be equipped with the knowledge and confidence to navigate difficult conversations. Continuous education and training might help to increase HCPs’ confidence in handling difficult consultations. Additionally, making the information materials for pregnant women available in multiple languages and incorporating more visuals to enhance comprehension could support HCPs in reaching a broader group of pregnant women.

•We modeled pertussis incidence in Israel between 1998 and 2019.•Our model identified a 4-year periodicity and a 325% increase in incidence between 2002 and 2014.•We observed a 59.7% decline from 2015 to 2019 compared to the model’s projection.•A sharper reduction of 71.2% was observed in infants of age two months and below.•This decline is partly attributable to the introduction of maternal Tdap vaccination.•Tdap vaccination during pregnancy is a promising tool towards controlling pertussis. Pertussis incidence in developed countries, including Israel, has increased over the past two decades despite the addition of two booster doses in children. However, as pertussis is characterized by a multi-annual periodicity, and since clinical diagnosis can miss cases, determining disease trends at the population level is challenging. To bridge this gap, we developed a simple statistical model to capture the temporal patterns of pertussis incidence in Israel. Our model was calibrated and tested using laboratory-confirmed cases of pertussis for the Israeli population between 1998 and 2019. The model identifies a clear four-year periodicity of pertussis incidence over the past two decades that is identical to the one observed in the pre-vaccine era. Accounting for this periodicity, the model shows a 325% increase in pertussis incidence from 2002 to 2014. These multi-year trends were interrupted shortly after the introduction of routine immunization of Tdap vaccine in pregnancy in 2015, after which we found a 59.7% (95% CI: 57.7–61.6%)decline in pertussis incidence and a 49.5% (36.0–61.6%) decline in hospitalizations compared to the model’s projection. While this sharp decline cannot be fully attributed to the newly introduced vaccination policy, sharper reductions of 71.2% (65.6–76.1%) in incidence and 58.4% (39.6–72.7%) in hospitalizations, have been observed in infants of age two months and below - young infants that have yet to become vaccinated and are more likely to be protected by maternal vaccination. Our work suggests that Tdap vaccination during pregnancy is a promising policy for controlling pertussis. Furthermore, due to the stable periodicity of pertussis, public health decision-makers should invest continuous efforts in the implementation of this strategy with additional reinforcement in expected peak years.