Vaccines最新文献

Background: The development of effective and safe vaccines and their timely delivery to the public play a crucial role in preventing and managing infectious diseases. Many vaccines have been produced and distributed globally to prevent COVID-19 infection. However, establishing effective vaccine development platforms and evaluating their safety and immunogenicity remains critical to increasing health security, especially in developing countries. Objectives: Therefore, we developed a local subunit vaccine candidate, RENOVAC, and reported its toxicity and immunogenicity profile in animal models. Methods: First, the synthetic gene-coding tandem RBD linked with the GS linker was cloned into the expression vector and expressed in CHO cells. The protein was then purified and filter sterilized, and 10 µg/dose and 25 µg/dose formulations were finally examined for the 14-day repeated dose toxicity followed by the immunogenic profile in preclinical studies. Results: When administered to Sprague Dawley rats by intramuscular route, the vaccine was well tolerated up to and including the dose of 25 µg/animal, and no toxicologically adverse changes were noted. The observed change in weight of the thymus and spleen might be related to the immunological response to the vaccine. The dimer RBD vaccine demonstrated the ability to generate high levels of specific immunoglobulins (IGs) and neutralization antibodies (NAbs). Finally, changes in the amounts of specific T cells and cytokines after vaccination suggested that the vaccine mainly triggers an immune response by activating CD4+ Th2-cells, which then activate B-cells to provide humoral immunity. Conclusions: The study suggests that, based on its reliable immunogenicity and acceptable safety, the vaccine can be further directed for clinical trials.

Background/objectives: The ongoing COVID-19 pandemic has underscored the need for alternative prophylactic measures, particularly for populations for whom vaccines may not be effective or accessible. This study aims to evaluate the efficacy of intranasally administered IgY antibodies derived from hen egg yolks as a protective agent against SARS-CoV-2 infection in Syrian golden hamsters, a well-established animal model for COVID-19.

Methods: Hens were immunized with the spike protein of SARS-CoV-2 to generate IgY antibodies. These antibodies were extracted from the egg yolks, purified, and their neutralizing activity was tested in vitro. Syrian golden hamsters were then treated with the IgY antibodies before being challenged with SARS-CoV-2. Viral loads were quantified using droplet digital PCR (ddPCR), and lung pathology was assessed through histopathological analysis.

Results: The in vitro assays showed that IgY effectively neutralized SARS-CoV-2. In the in vivo hamster model, IgY treatment led to a significant reduction in viral loads and a marked decrease in lung consolidation and inflammation compared to the positive control group. Histopathological findings further supported the protective role of IgY in reducing lung damage caused by SARS-CoV-2.

Conclusions: The results demonstrate that IgY antibodies exhibit strong antiviral activity and can significantly reduce SARS-CoV-2 viral loads and associated lung pathology in hamsters. These findings suggest that IgY could be a viable prophylactic option for preventing SARS-CoV-2 infection, particularly for individuals who cannot receive or respond to vaccines. Further studies are warranted to optimize dosage and explore the long-term efficacy of IgY antibodies.

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mRNA vaccines represent a milestone in the history of vaccinology, because they are safe, very effective, quick and cost-effective to produce, easy to adapt should the antigen vary, and able to induce humoral and cellular immunity.

Methods: To date, only two COVID-19 mRNA and one RSV vaccines have been approved. However, several mRNA vaccines are currently under development for the prevention of human viral (influenza, human immunodeficiency virus [HIV], Epstein-Barr virus, cytomegalovirus, Zika, respiratory syncytial virus, metapneumovirus/parainfluenza 3, Chikungunya, Nipah, rabies, varicella zoster virus, and herpes simplex virus 1 and 2), bacterial (tuberculosis), and parasitic (malaria) diseases.

Results: RNA viruses, such as severe acute respiratory syndrome coronavirus (SARS-CoV)-2, HIV, and influenza, are characterized by high variability, thus creating the need to rapidly adapt the vaccines to the circulating viral strain, a task that mRNA vaccines can easily accomplish; however, the speed of variability may be higher than the time needed for a vaccine to be adapted. mRNA vaccines, using lipid nanoparticles as the delivery system, may act as adjuvants, thus powerfully stimulating innate as well as adaptive immunity, both humoral, which is rapidly waning, and cell-mediated, which is highly persistent. Safety profiles were satisfactory, considering that only a slight increase in prognostically favorable anaphylactic reactions in young females and myopericarditis in young males has been observed.

Conclusions: The COVID-19 pandemic determined a shift in the use of RNA: after having been used in medicine as micro-RNAs and tumor vaccines, the new era of anti-infectious mRNA vaccines has begun, which is currently in great development, to either improve already available, but unsatisfactory, vaccines or develop protective vaccines against infectious agents for which no preventative tools have been realized yet.

Background and Objectives: Given that COVID-19 vaccination is a relatively recent development, particularly when compared to immunisation against other diseases, it is crucial to assess its efficacy in vaccinated populations. This literature review analysed studies that monitored antibody titres against SARS-CoV-2 in healthcare workers who received COVID-19 vaccines. Methods: Using the PICO (Population, Intervention, Comparators, Outcomes) model recommended in the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines we included 43 publications which analyse antibody dynamics following primary vaccination, the effects of booster doses, and the influence of factors such as COVID-19C infection, age, and sex on antibody kinetics. Results: All the studies demonstrated a strong immunogenic response to the vaccines. Re-gardless of the vaccine used, over 95% of the pre-vaccination seronegative population be-came seropositive in all studies. Depending on the sampling intervals provided by the re-searchers, antibody levels were quantitatively highest during the first three months after vaccination, but levels inevitably declined over time. The monthly decline in antibodies observed in all these studies highlighted the necessity for booster doses. Studies analysing the impact of revaccination on antibody dynamics have confirmed that revaccination is an effective tool to boost humoral immunity against SARS-CoV-2. An-tibodies appear to persist for a longer period of time after revaccination, although they are subject to similar factors influencing antibody dynamics, such as age, comorbidities, and exposure to COVID-19. In addition, heterogeneous revaccination strategies have been shown to be more effective than homogeneous revaccination. Conclusions: Our review demonstrated that antibody levels against SARS-CoV-2 inevitably decline after vaccination, leaving the question of ongoing booster strategies open. The studies reviewed provided evidence of the effectiveness of booster vaccination, despite differences in age, sex, and prior COVID-19 infection. This suggests that repeated vaccination remains a highly effective method for mitigating the continued threat posed by COVID-19.

Background/Objective: Duck virus hepatitis (DVH), caused by duck hepatitis A virus (DHAV), poses significant challenges to duck farming due to high mortality rates in young ducklings. Despite the widespread use of live attenuated vaccines, the genetic diversity within DHAV strains has diminished their cross-protection efficacy. This study aimed to evaluate the cross-protective efficacy of current DHAV-1 and DHAV-3 vaccines against genetically divergent wild strains. Methods: Phylogenetic analyses of the VP1 genes from DHAV-1 and DHAV-3 were conducted. Both DHAV-1 and DHAV-3 vaccines were tested in ducklings, with and without maternal-derived antibodies (MDA), through challenge trials with homologous and heterologous strains. Results: In the phylogenetic analysis, compared to vaccine strains, DHAV-1 and DHAV-3 field variant strains were classified into different genotypes. In ducklings without MDA, the DHAV-1 vaccine provided 60% survival against homologous strains by 2 days post-vaccination (DPV) and complete protection by 4 DPV, while survival rates against heterologous strains ranged from 40 to 60%. In ducklings with MDA, the DHAV-1 vaccine provided full protection with an additional vaccination for day-old ducklings against heterologous strains. The DHAV-3 vaccine conferred complete protection against both homologous and heterologous strains by 2 DPV, regardless of MDA presence. Conclusions: The DHAV-3 vaccine demonstrated robust cross-protection across genotypes, while the DHAV-1 vaccine showed limitations against genetically divergent strains. These findings highlight the necessity for genotype-matched vaccines and optimized immunization strategies to enhance protection against evolving DHAV field strains.

Background: Persistent inequities in access to vaccinations pose challenges for immunization programs worldwide. Innovations facilitating vaccine delivery, such as leveraging vaccine thermostability through a Controlled Temperature Chain (CTC), have emerged as a potential solution to increase coverage in low- and middle-income countries (LMICs) countries such as Côte d'Ivoire, reducing dependence on the cold chain and improving vaccine delivery efficiency. However, the added value of thermostable vaccines and their integration into national immunization programs is under-recognized by stakeholders. This consultation aimed to convene key immunization stakeholders in Côte d'Ivoire in order to examine their perceptions regarding the value of vaccine thermostability to address barriers to outreach and equity in immunization programs.

Methods: A novel workshop model involving structured group discussions was used to document the viewpoints of national stakeholders representing different areas of the immunization program. They prioritized barriers undermining coverage and equity in their country and explored the potential impact of CTC on the immunization program in the context of thermostable vaccines. The vaccines discussed were for Hepatitis B, Human Papillomavirus, and Meningitis.

Results: The workshop outcomes highlighted the context and vaccine-specific variation of the importance of certain barriers, emphasizing the need for tailored strategies. The barriers considered most likely to be alleviated by vaccine thermostability were under the categories of human resource management, vaccine supply and logistics, and services delivery. The least relevant category of barriers concerned demand generation.

Conclusions: The consultation provided valuable insights into stakeholder perspectives, priorities, and conditions for the effective integration of thermostable vaccines, informing future product development and policy decisions to optimize vaccine delivery and address immunization challenges in LMICs.

Objectives: This study aimed to evaluate the immunogenicity and safety of a 13-valent pneumococcal polysaccharide conjugate vaccine (CRM197/TT) (PCV13i) in infants.

Methods: A total of 1200 infants were randomly assigned to either the experimental PCV13i group or the control PCV13 group in a 1:1 ratio. Each group received a three-dose series of the vaccine at 2, 4, and 6 months of age, followed by a booster dose at 12-15 months. Blood samples were collected before and 30 days after both primary and booster vaccinations. The primary immunogenicity endpoints were the seropositive rate and the geometric mean concentration (GMC) of IgG antibodies against the 13 pneumococcal serotypes. The primary safety endpoint was the incidence of adverse reactions within 0-7 days and 0-30 days after vaccination.

Results: Results showed that the experimental PCV13i was well tolerated, with a safety profile comparable to that of the control vaccine. Following primary vaccination, the GMCs of IgG responses against serotypes 1, 5, 6A, 6B, 14, and 18C in the experimental group were lower than those in the control group, while responses against serotypes 3, 4, 7F, 9V, 19A, 19F, and 23F were higher. The experimental group exhibited higher opsonophagocytic killing assay (OPA) geometric mean titers (GMTs) for serotypes 3, 7F, 19A, and 19F compared to the control group, while GMTs for serotypes 1, 5, 6A, and 18C were lower. Following booster vaccination, OPA GMTs of the experimental group remained higher than those of the control group for serotypes 3, 7F, and 19F, while GMTs for serotype 5 were lower. Both vaccines induced robust immune responses, with high seropositive rates and significant increases in antibody levels following vaccination.

Conclusions: The experimental PCV13i demonstrated non-inferiority to the control PCV13 in terms of immunogenicity.

Background: Vaccination is one of the most effective measures to prevent influenza illness and its complications. Since the 1980s, countries and territories in the Americas have progressively implemented influenza vaccination operations in high-risk priority groups-such as older adults, pregnant persons, persons with comorbidities and health workers. Methods: In this review, we present the history and progress of the seasonal influenza program in the Americas, how the program contributed to the efficient and timely roll-out of the COVID-19 vaccines during the pandemic, and how the program can be used to promote immunization operations across the life span for existing and future vaccines. Results: The influenza A(H1N1)pdm09 pandemic in 2009 and the COVID-19 pandemic in 2020-2023 underscored the importance of having a robust seasonal influenza vaccination program for pandemic preparedness and response. Overall, countries with existing seasonal influenza vaccination programs were better prepared and rolled out the delivery of COVID-19 vaccines more quickly and effectively compared to other countries where the influenza vaccination platform was weak or non-existent. Conclusions: Traditionally, national immunization programs of developing countries have been predominately focused on newborns, children younger than five years and school-aged children while often limiting their investment in effective adult vaccination programs; these programs are typically isolated to high-income countries. Countries in Latin America have been the exception, with strong influenza vaccination programs for adults regardless of national income level. The presence of functional and effective adult influenza vaccination programs can also facilitate the acceptance and uptake of other adult vaccines targeting priority groups at higher risk for severe illness or complications.

This report examines the evolving role of coronavirus disease 2019 (COVID-19) vaccination in Japan, especially in light of the reduced public concern following the reclassification of COVID-19 as a Category 5 infectious disease in May 2023. With over half the population estimated to have hybrid immunity from prior infections and vaccinations, this report evaluated the necessity and frequency of additional booster doses. Despite strong recommendations from Japanese medical societies to continue vaccination, public skepticism remains owing to financial burdens, adverse reactions, and the perceived limited benefits of frequent boosters. Studies on antibody responses have revealed that individuals with hybrid immunity maintain robust protection with significantly elevated antibody titers that persist over extended periods. Case studies have indicated durable immunity among individuals who have both been vaccinated and experienced breakthrough infections, raising questions about the need for uniform booster policies. This report also discusses the newly approved replicon-type (self-amplifying) vaccines currently available only in Japan, which have generated public and professional debates regarding their efficacy and safety. A more personalized approach to vaccination that takes into account the antibody titers, prior infection history, and individual choices is recommended. Finally, this report underscores the importance of aligning vaccination policies with scientific evidence and public sentiment to optimize COVID-19 countermeasures in Japan.