Clinical repercussions in pertussis infants post-Tdpa vaccination of pregnant woman: An immunization success?

The Tdap Vaccination in Pregnancy: Results of a Healthy Equity Audit on Coverage Trends and Their Determinants in the Reggio Emilia Province (Italy)

Background/Objectives: The Italian National Plan for Vaccine Prevention 2017-2019 recommended tetanus, diphtheria, and acellular pertussis vaccines (Tdap) for pregnant women, irrespectively of their immunization history. This study aims to describe the coverage rate trends for Tdap vaccination in pregnancy and evaluate the differences by socioeconomic status. Methods: This is a retrospective analysis within a health equity audit of the Local Health Authority of Reggio Emilia on vaccination in pregnancy from 2018 (a local vaccination campaign) to 2023. All women residents in our area who gave birth during that period were included and linked to the electronic Registry of Immunization Service. The vaccination coverage in pregnant women was analyzed over time and stratified by pregnant women's sociodemographic and obstetric characteristics. Results: The coverage of Tdap in pregnant women of the Province of Reggio Emilia increased from 15.9% in 2018 to 53.9% in 2023. The coverage was higher among Italians, women with higher educational levels (aPR 1.49 (CI95%1.41-1.57)), within 31-35 years of age (aPR 1.37 (CI95% 1.28-1.46)), occupied, nulliparous (aPR multiparous vs nulliparous: 0.76 (0.74; 0.78)), and followed in the private sector (aPR 1.07 (1.03-1.11)). Inequalities in coverage increased during the study period for women assisted in the private sector, while decreased or remained stable for women assisted in the context of public services. Conclusions: The vaccination promotion campaign in Reggio Emilia helped increase Tdap coverage in pregnancy from 16 to 53%. Nevertheless, the coverage rates of the most disadvantaged women are still several points lower than the average.

Pertussis Vaccine Candidate Based on Outer Membrane Vesicles Derived From Biofilm Culture

Outer membrane vesicles (OMV) derived from Bordetella pertussis-the etiologic agent of the resurgent disease called pertussis-are safe and effective in preventing bacterial colonization in the lungs of immunized mice. Vaccine formulations containing those OMV are capable of inducing a mixed Th1/Th2/Th17 profile, but even more interestingly, they may induce a tissue-resident memory immune response. This immune response is recommended for the new generation of pertussis-vaccines that must be developed to overcome the weaknesses of current commercial acellular vaccines (second-generation of pertussis vaccine). The third-generation of pertussis vaccine should also deal with infections caused by bacteria that currently circulate in the population and are phenotypically and genotypically different [in particular those deficient in the expression of pertactin antigen, PRN(-)] from those that circulated in the past. Here we evaluated the protective capacity of OMV derived from bacteria grown in biofilm, since it was observed that, by difference with older culture collection vaccine strains, circulating clinical B. pertussis isolates possess higher capacity for this lifestyle. Therefore, we performed studies with a clinical isolate with good biofilm-forming capacity. Biofilm lifestyle was confirmed by both scanning electron microscopy and proteomics. While scanning electron microscopy revealed typical biofilm structures in these cultures, BipA, fimbria, and other adhesins described as typical of the biofilm lifestyle were overexpressed in the biofilm culture in comparison with planktonic culture. OMV derived from biofilm (OMVbiof) or planktonic lifestyle (OMVplank) were used to formulate vaccines to compare their immunogenicity and protective capacities against infection with PRN(+) or PRN(-) B. pertussis clinical isolates. Using the mouse protection model, we detected that OMVbiof-vaccine was more immunogenic than OMVplank-vaccine in terms of both specific antibody titers and quality, since OMVbiof-vaccine induced antibodies with higher avidity. Moreover, when OMV were administered at suboptimal quantity for protection, OMVbiof-vaccine exhibited a significantly adequate and higher protective capacity against PRN(+) or PRN(-) than OMVplank-vaccine. Our findings indicate that the vaccine based on B. pertussis biofilm-derived OMV induces high protection also against pertactin-deficient strains, with a robust immune response.