Decennial administration in young adults of a reduced-antigen content diphtheria, tetanus, acellular pertussis vaccine containing two different concentrations of aluminium

Effectiveness of maternal immunisation with a three-component acellular pertussis vaccine at preventing pertussis in infants in the United States: Post-hoc analysis of a case-control study using Bayesian dynamic borrowing

BACKGROUND

Immunisation during pregnancy with a tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine can protect infants against pertussis between birth and paediatric vaccination. We aimed to estimate the vaccine effectiveness (VE) of third-trimester pregnancy immunisation with the three-component acellular pertussis (Td3ap) vaccine at preventing pertussis in infants <2 months in the United States (US), to support a label update.

METHODS

We performed a post-hoc sub-analysis of a case-control study conducted in six US Emerging Infections Program Network states between 2011 and 2014. Our analysis included only cases and controls whose mothers were either vaccinated with Td3ap or did not receive any Tdap vaccine. The association between Td3ap maternal immunisation and pertussis in infants was assessed for US data using a frequentist method with conditional logistic regression. A robustified analysis was conducted using Bayesian dynamic borrowing of non-US data, considering a mixing-weighted prior of 90% for historical non-US VE data, and of 10% for a vague prior. VE was estimated as (1-odds ratio) × 100%. Sensitivity analyses accounting for the impact of each non-US study, different mixing weights and missing/ambiguous data were performed.

RESULTS

We included 108 cases and 183 controls. Based on US data, the estimated VE of third-trimester maternal immunisation with Td3ap at preventing pertussis in infants <2 months was 78.0% (95% confidence interval: -38.0; 96.5). VE estimated by Bayesian dynamic borrowing of non-US data (with a 90% weight for historical data) was 83.4% (95% credible interval: 55.7; 92.5); sensitivity analyses produced similar VE estimates.

CONCLUSIONS

Effectiveness of third-trimester pregnancy immunisation with Td3ap at preventing infant pertussis in the US is very likely to be ≥ 50% and is most likely ∼ 80%. Bayesian dynamic borrowing of non-US VE data allowed overcoming the limited power (due to small sample size) of a brand-specific sub-analysis by considering additional evidence.

Antibody persistence and safety and immunogenicity of a second booster dose nine years after a first booster vaccination with a reduced antigen diphtheria-tetanus-acellular pertussis vaccine (Tdap) in adults

BACKGROUND

Over the last decades, pertussis showed periodic increases in its incidence among adults, despite being a vaccine-preventable disease.

METHODS

This phase III, multicenter, extension study (NCT00489970) was conducted in adults from the United States, followed at Year (Y) 5 and Y9 post-vaccination with a dose of reduced-antigen-content tetanus-diphtheria-acellular pertussis vaccine containing either 3 (Tdap-B group) or 5 pertussis components (Tdap-A group). Willing participants in Tdap groups and newly-recruited participants (Control group) received one Tdap-B dose at Y9. Antibody persistence (at Y5 and Y9) and safety of Tdap-B at Y9 were assessed. Non-inferiority of immune response elicited by 2 Tdap doses was evaluated at Y9: (i) versus one Tdap-B dose for diphtheria and tetanus in terms of seroprotection rates; (ii) for all antigens in terms of booster response rates (Tdap-B and Tdap-A groups versus Control group); and (iii) for pertussis antigens in terms of geometric mean concentrations (GMCs) versus a 3-dose series of a combined diphtheria-tetanus-acellular pertussis vaccine (DTPa) administered during infancy.

RESULTS

1257 participants were enrolled at Y5 and 809 participants were vaccinated at Y9. Seroprotection rates in both Tdap groups were ≥98.4% and ≥98.0% (Y5) and ≥98.3% and ≥98.1% (Y9) for diphtheria and tetanus, respectively. For pertussis antigens, antibody concentrations above assay cut-offs were observed for ≥76.6% (Y5) and ≥84.9% (Y9) of participants in Tdap groups. At Y9, one month post-Tdap vaccination, comparable seroprotection/seropositivity rates and antibody GMCs were observed among groups. Non-inferiority of immune responses in both Tdap groups was demonstrated when compared to the Control group for diphtheria and tetanus and to a 3-dose DTPa series for pertussis antigens. Non-inferiority criteria in terms of booster response were not met for all antigens. No safety concerns were raised.

CONCLUSION

A second dose of Tdap-B administered in adults, 9 years after initial Tdap vaccination, is immunogenic and well-tolerated.

Immunogenicity and safety of a second booster dose of an acellular pertussis vaccine combined with reduced antigen content diphtheria-tetanus toxoids 10 years after a first booster in adolescence: An open, phase III, non-randomized, multi-center study

Pertussis is a highly contagious disease, for which periodic peaks in incidence and an increasing number of outbreaks have been observed over the last decades. The reduced-antigen-content tetanus-diphtheria-acellular pertussis vaccine (Tdap) can be used to boost individuals aged ≥10 years, vaccinated in infancy with a diphtheria-tetanus-acellular pertussis vaccine (DTaP), to reduce pertussis morbidity and maintain protection against diphtheria and tetanus throughout adolescence and adulthood. This phase III, open-label, non-randomized, multicenter follow-up study (NCT01738477) enrolled 19–30-year-old participants from the United States who had received booster vaccination 10 years earlier with either Tdap (Tdap group) or Td (Td group). In total, 128 (Tdap group) and 37 (Td group) participants received Tdap vaccination. After administration of Tdap, all participants were seroprotected (antibody concentrations ≥0.1 international units [IU]/ml) against diphtheria and tetanus. Immune responses to a second Tdap dose in the Tdap group were shown to be non-inferior to responses elicited by a first Tdap dose in the Td group for diphtheria and tetanus and to a 3-dose DTaP vaccination during infancy for pertussis antigens (primary objectives). Post-booster vaccination, all participants in both groups had antibody concentrations above assay cut-offs and antibody geometric mean concentrations increased by 3.8–15.5-fold compared to pre-booster levels for all antigens. The incidence of adverse events was similar in the Td (80.6%) and Tdap (85.6%) groups (no serious adverse events reported). A Tdap dose administered after previous Td or Tdap vaccination was shown to be immunogenic and well-tolerated in young adults, supporting repeated vaccination with Tdap at 10-year intervals.

A phase I, randomized, controlled, dose-ranging study of investigational acellular pertussis (aP) and reduced tetanus-diphtheria-acellular pertussis (TdaP) booster vaccines in adults

Despite high vaccination coverage worldwide, pertussis has re-emerged in many countries. This randomized, controlled, observer-blind phase I study and extension study in Belgium (March 2012-June 2015) assessed safety and immunogenicity of investigational acellular pertussis vaccines containing genetically detoxified pertussis toxin (PT) (NCT01529645; NCT02382913). 420 healthy adults (average age: 26.8 ± 5.5 years, 60% female) were randomized to 1 of 10 vaccine groups: 3 investigational aP vaccines (containing pertussis antigens PT, filamentous hemagglutinin [FHA] and pertactin [PRN] at different dosages), 6 investigational TdaP (additionally containing tetanus toxoid [TT] and diphtheria toxoid [DT]), and 1 TdaP comparator containing chemically inactivated PT. Antibody responses were evaluated on days 1, 8, 30, 180, 365, and approximately 3 years post-booster vaccination. Cell-mediated immune responses and PT neutralization were evaluated in a subset of participants in pre-selected groups. Local and systemic adverse events (AEs), and unsolicited AEs were collected through day 7 and 30, respectively; serious AEs and AEs leading to study withdrawal were collected through day 365 post-vaccination. Antibody responses against pertussis antigens peaked at day 30 post-vaccination and then declined but remained above baseline level at approximately 3 years post-vaccination. Responses to FHA and PRN were correlated to antigen dose. Antibody responses specific to PT, toxin neutralization activity and persistence induced by investigational formulations were similar or significantly higher than the licensed vaccine, despite lower PT doses. Of 15 serious AEs, none were considered vaccination-related; 1 led to study withdrawal (premature labor, day 364; aP4 group). This study confirmed the potential benefits of genetically detoxified PT antigen. All investigational study formulations were well tolerated.

Strategies and new developments to control pertussis, an actual health problem

The aim of this article is to describe the current epidemiological situation of pertussis, as well as different short-term strategies that have been implemented to alleviate this threat. The state of the art of the development of new vaccines that are expected to provide long-lasting immunity against pertussis was also included.