Safety and efficacy of combination vaccines

Acceptance and willingness to pay for DTaP-HBV-IPV-Hib hexavalent vaccine among parents: A cross-sectional survey in China

DTaP-HBV-IPV-Hib hexavalent vaccine has been used in high-income countries for many years to prevent diphtheria, tetanus, pertussis, hepatitis B, poliomyelitis, and invasive Haemophilus influenzae type b disease. Currently, no hexavalent vaccines have been approved for use in China. Evidence of parental acceptance and interest in hexavalent vaccines can help policy makers and manufacturers make decisions about entering the vaccine market and the immunization program in China. We measured parental acceptance and willingness-to-pay (WTP) for a hexavalent vaccine to provide such evidence. We conducted a cross-sectional survey of children's caregivers in 16 vaccination clinics in seven cities in China and obtained information on socio-demographics, knowledge of disease, confidence in vaccines, previous vaccination experience, and acceptance of and WTP for hexavalent vaccine. Multivariate logistic regression was used to determine factors influencing acceptance, and multivariate tobit regression was used to identify factors impacting WTP. Between April 28 and June 30, 2023, a total of 581 parents of children aged 0-6 years participated in the survey; 435 (74.87%, 95% CI:71.3%-78.4%) parents indicated acceptance of hexavalent vaccine. Residence location, parents' education level, experience paying for vaccination, and disease knowledge scores were key factors affecting parents' choices for vaccination. Mean (SD) and median (IQR) willingness to pay for full 4-dose course vaccination were 2266.66 (1177.1) CNY and 2400 (1600-2800) CNY. Children's age (p < .001), parents' education level (p = .024), and perceived price barriers (p < .001) were significantly associated with WTP. Parents have high acceptance and willingness to pay for hexavalent vaccine. The less money parents have to pay out of pocket, the more willing they can be to accept the vaccine. Therefore, acceptance may increase even further if the vaccine is covered by medical insurance, provided free of charge by the government, or if its price is reduced. Our results provide reference for optimizing and adjusting immunization strategies in China.

Improving Innovation and Access to Combination Vaccines for Childhood Immunization in China

BACKGROUND

combination vaccines can improve timely vaccination coverage and mitigate the social and economic burdens of both caregivers and health systems. Compared to other countries with high immunization performance, China remains behind the curve in promoting the inclusion of new combination vaccines into national vaccination schedules. The domestic research and development pipeline faces many technical obstacles, regulatory pressures, and competitive opposition. In addition to this, health disparities regarding combination vaccines exist in each dimension of access and their determinants, including availability, accessibility, acceptability, and quality. Our study aims to provide a cross-disciplinary analysis of China's combination vaccines (from innovation to access) and identify the main factors that affect the attitudes and behavior choices for combination vaccines.

METHOD

systematic reviews and secondary data analysis will be conducted to map the landscape of combination vaccines in China and the determinants influencing their innovation and access. A cross-sectional survey will be performed in seven provinces of China based on geo-economic representativeness among caregivers with children that are between 2 and 24 months old and are registered in the national immunization system. Questionnaires will be used to examine the relationship between each dimension of access and their determinants. These questionnaires will cover the caregivers' knowledge, attitude, and willingness to pay for combination vaccines, as well as their perceptions about vaccination services. Semi-structured interviews with the suppliers (public and private) and healthcare providers will help identify research gaps and the key challenges they face when developing and introducing combination vaccines in China.

DISCUSSION

using a combined approach, with cross-country and multi-disciplinary support from experts, our research is designed to fill the information gaps in China's combination vaccine industry across the innovation-access spectrum. It will lead to evidence-based recommendations which will foster greater access to innovation-enhancing combination vaccines for childhood immunization in China. Moreover, the multi-dimensional approach could also be adapted beyond combination vaccines to assess innovation and other public goods for health among disadvantaged groups in the future.

COVID-19 and Seasonal Influenza Vaccination: Cross-Protection, Co-Administration, Combination Vaccines, and Hesitancy

SARS-CoV-2 and influenza are the main respiratory viruses for which effective vaccines are currently available. Strategies in which COVID-19 and influenza vaccines are administered simultaneously or combined into a single preparation are advantageous and may increase vaccination uptake. Here, we comprehensively review the available evidence on COVID-19/influenza vaccine co-administration and combination vaccine candidates from the standpoints of safety, immunogenicity, efficacy, policy and public acceptance. While several observational studies have shown that the trained immunity induced by influenza vaccines can protect against some COVID-19-related endpoints, it is not yet understood whether co-administration or combination vaccines can exert additive effects on relevant outcomes. In randomized controlled trials, co-administration has proved safe, with a reactogenicity profile similar to that of either vaccine administered alone. From the immunogenicity standpoint, the immune response towards four influenza strains and the SARS-CoV-2 spike protein in co-administration groups is generally non-inferior to that seen in groups receiving either vaccine alone. Several public health authorities have advocated co-administration. Different combination vaccine candidates are in (pre)-clinical development. The hesitancy towards vaccine co-administration or combination vaccines is a multifaceted phenomenon and may be higher than the acceptance of either vaccine administered separately. Public health implications are discussed.

Evaluation of Potency on Diphtheria and Tetanus Toxoid for Adult Vaccines by In Vivo Toxin Neutralization Assay Using National Reference Standards

Objectives

Vaccinations against diphtheria and tetanus are essential in providing immunity against these bacterial infections. The potency of diphtheria and tetanus toxoid vaccines can be measured using the in vivo toxin neutralization assay. The limit of potency of this assay was determined only for children. Therefore, we assessed the potency of adult vaccines using this assay to identify the feasibility of limit for adult vaccines.

Methods

Fifteen lots of tetanus-reduced diphtheria and tetanus-diphtheria-acellular pertussis vaccines were used. In vivo toxin neutralization and lethal challenge assays were conducted on each vaccine to calculate the potencies of the toxoids. National reference standards for toxins and antitoxins were used for in vivo toxin neutralization assay.

Results

All 15 lots satisfied the limits of potency for lethal challenge assay. The potency of diphtheria and tetanus toxoids exceeded 1 and 8 units/mL, respectively, for in vivo toxin neutralization assay.

Conclusion

Although additional studies are required for new assays and limits, the current level of potency for adult vaccines as determined by in vivo toxin neutralization assay, was demonstrated in this study. Such efforts to improve assays are expected to promote the development of diphtheria and tetanus vaccines for adults and to contribute to vaccine self-sufficiency.

Factors underlying suboptimal childhood immunisation

This review considers possible reasons behind parents' missed vaccination opportunities in the context of the latest immunisation coverage rates for England. Suboptimal uptake is not exclusive to measles, mumps and rubella (MMR). A substantial proportion of children also miss diphtheria, tetanus and polio vaccination. For MMR and diphtheria, tetanus and polio, uptake of primary plus booster immunisation is lower than for the primary course alone. Several reasons for suboptimal uptake are identified from the international literature. These provide insights into parental decision-making and potential barriers to immunisation that may need to be addressed in efforts to improve coverage rates.

Childhood and malaria vaccines combined in biodegradable microspheres produce immunity with synergistic interactions

Biodegradable microspheres may represent a potential tool for the delivery of combination vaccines. We demonstrate strong immunogenicity of five co-encapsulated antigens after a single subcutaneous inoculation in guinea pigs. Tetanus- and diphtheria-specific antibodies were not significantly affected by the presence of either antigen or by the presence of pertussis or Haemophilus influenzae type b (Hib) antigens. Microsphere formulations gave better protection against diphtheria toxin than did two injections of a licensed tetravalent vaccine. Finally, a synthetic malaria peptide antigen (PfCS) also encapsulated in PLGA microspheres increased diphtheria and tetanus-specific immunity and improved protection against diphtheria. These findings demonstrate the potential of microspheres as an alternative and promising strategy for combination vaccines with a further aptitude in reducing the number of inoculations required to gain functional immunity.