Skin-patch delivered subunit vaccine induces broadly neutralising antibodies against SARS-CoV-2 variants of concern

Microarray patches likely to reduce the operational costs of immunization: A Monte Carlo simulation study

Development of microneedle array patches (MAPs) for potential use in immunization is ongoing, but the cost of manufacturing is expected to be higher than that of existing needle-and-syringe vial systems. The potential benefits of MAPs in reaching previously unvaccinated populations have been touted, but affordability, especially in low- and middle-income countries, remains an open question. In this study, we quantify the expected impact on operational costs of switching to MAPs for immunization for measles-rubella, human papilloma virus, and typhoid in both routine and campaign-based delivery modes. We endeavor to make a comprehensive estimate, including the costs of labor, syringes, waste management (i.e., sharps and trash), wastage (unused vaccine), freight and in-country cold chain transportation. We examined five potential use cases and our results show that in total, operational cost savings from a switch to MAPs are expected to range from a low of $0.24 per dose delivered (HPV, 1-dose vial, campaign) up to $0.61 per dose delivered (MR, 10-dose vial, routine). Excluding the allocated cost of labor, the estimated range of cost savings are $0.18 and $0.43, respectively. Confidence intervals are wide, due to the uncertainty in the assumptions, but in all five use cases tested, there was at least an 87 % probability of savings. These results show that operational savings from a switch to MAPs may offset at least part of the expected incremental manufacturing costs, which will make the transition more viable in settings with limited budget space. With this in mind, development agencies should continue to invest in MAPs technology and, if the product does come to market, use this evidence as part of total value of vaccines assessments and to inform investment strategies for implementation of vaccine MAPs, including alignment with policy makers.

Skin patch delivery of a SARS-CoV-2 spike DNA vaccine produces broad neutralising antibody responses

The ongoing SARS-CoV-2 pandemic continues to be a major health burden globally, especially in resource-limited areas. Continued research into more effective and accessible vaccines is required to reduce the burden of disease. Here, we use an emerging vaccine delivery system, the high-density microarray patch (HD-MAP) to deliver a plasmid DNA vaccine (Delta 6P) encoding for the SARS-CoV-2 spike protein. HD-MAP delivery of this vaccine resulted in robust IgG responses in mice against multiple domains of the spike protein. The cellular response to vaccination was also measured, and comparative analysis showed that relative to intramuscular vaccination, HD-MAP vaccination elicited spike-specific CD4+ T and CD8+ T cell responses that were largely comparable, but the number of polyfunctional CD4+ T cells was higher in the HD-MAP group. Collectively, this work suggests that HD-MAP delivery of the Delta 6P vaccine is effective against SARS-CoV-2, warranting further investigation.

Innovations and Challenges in the Development of COVID-19 Vaccines for a Safer Tomorrow

Vaccination, a historically effective public health intervention, has shielded millions from various diseases. Lessons from severe acute respiratory syndrome coronavirus (SARS-CoV) have improved COVID-19 vaccine development. Despite mRNA vaccines' efficacy, emerging variants pose challenges, exhibiting increased transmissibility, infectivity, and severity. Developing COVID-19 vaccines has faced hurdles due to urgency, limited virus understanding, and the need for safe solutions. Genetic variability necessitates continuous vaccine adjustments and production challenges demand scaling up manufacturing with stringent quality control. This review explores SARS-CoV-2's evolution, upcoming mutations that challenge vaccines, and strategies such as structure-based, T cell-based, respiratory mucosal-based, and nanotechnology approaches for vaccine development. This review insight provides a roadmap for navigating virus evolution and improving vaccine development.

Enhancement of cellular immunity following needle-free vaccination of mice with SARS-CoV-2 spike protein

The COVID-19 pandemic has highlighted the need for vaccines capable of providing rapid and robust protection. One way to improve vaccine efficacy is delivery via microarray patches, such as the Vaxxas high-density microarray patch (HD-MAP). We have previously demonstrated that delivery of a SARS-CoV-2 protein vaccine candidate, HexaPro, via the HD-MAP induces potent humoral immune responses. Here, we investigate the cellular responses induced by HexaPro HD-MAP vaccination. We found that delivery via the HD-MAP induces a type one biassed cellular response of much greater magnitude as compared to standard intramuscular immunization.

Advanced Vaccine Design Strategies against SARS-CoV-2 and Emerging Variants

Vaccination is the most cost-effective means in the fight against infectious diseases. Various kinds of vaccines have been developed since the outbreak of COVID-19, some of which have been approved for clinical application. Though vaccines available achieved partial success in protecting vaccinated subjects from infection or hospitalization, numerous efforts are still needed to end the global pandemic, especially in the case of emerging new variants. Safe and efficient vaccines are the key elements to stop the pandemic from attacking the world now; novel and evolving vaccine technologies are urged in the course of fighting (re)-emerging infectious diseases. Advances in biotechnology offered the progress of vaccinology in the past few years, and lots of innovative approaches have been applied to the vaccine design during the ongoing pandemic. In this review, we summarize the state-of-the-art vaccine strategies involved in controlling the transmission of SARS-CoV-2 and its variants. In addition, challenges and future directions for rational vaccine design are discussed.

Microarray patches: scratching the surface of vaccine delivery

INTRODUCTION

Microneedles are emerging as a promising technology for vaccine delivery, with numerous advantages over traditional needle and syringe methods. Preclinical studies have demonstrated the effectiveness of MAPs in inducing robust immune responses over traditional needle and syringe methods, with extensive studies using vaccines targeted against different pathogens in various animal models. Critically, the clinical trials have demonstrated safety, immunogenicity, and patient acceptance for MAP-based vaccines against influenza, measles, rubella, and SARS-CoV-2.

AREAS COVERED

This review provides a comprehensive overview of the different types of microarray patches (MAPs) and analyses of their applications in preclinical and clinical vaccine delivery settings. This review also covers additional considerations for microneedle-based vaccination, including adjuvants that are compatible with MAPs, patient safety and factors for global vaccination campaigns.

EXPERT OPINION

MAP vaccine delivery can potentially be a game-changer for vaccine distribution and coverage in both high-income and low- and middle-income countries. For MAPs to reach this full potential, many critical hurdles must be overcome, such as large-scale production, regulatory compliance, and adoption by global health authorities. However, given the considerable strides made in recent years by MAP developers, it may be possible to see the first MAP-based vaccines in use within the next 5 years.

Monoclonal Antibodies Specific for SARS-CoV-2 Spike Protein Suitable for Multiple Applications for Current Variants of Concern

The global coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spawned an ongoing demand for new research reagents and interventions. Herein we describe a panel of monoclonal antibodies raised against SARS-CoV-2. One antibody showed excellent utility for immunohistochemistry, clearly staining infected cells in formalin-fixed and paraffin embedded lungs and brains of mice infected with the original and the omicron variants of SARS-CoV-2. We demonstrate the reactivity to multiple variants of concern using ELISAs and describe the use of the antibodies in indirect immunofluorescence assays, Western blots, and rapid antigen tests. Finally, we illustrate the ability of two antibodies to reduce significantly viral tissue titers in K18-hACE2 transgenic mice infected with the original and an omicron isolate of SARS-CoV-2.

Effective vaccination strategy using SARS-CoV-2 spike cocktail against Omicron and other variants of concern

The SARS-CoV-2 Omicron variant harbors more than 30 mutations in its spike (S) protein. Circulating Omicron subvariants, particularly BA5 and other variants of concern (VOCs), show increased resistance to COVID-19 vaccines that target the original S protein, calling for an urgent need for effective vaccines to prevent multiple SARS-CoV-2 VOCs. Here, we evaluated the neutralizing activity and protection conferred by a BA1-S subunit vaccine when combined with or used as booster doses after, administration of wild-type S protein (WT-S). A WT-S/BA1-S cocktail, or WT-S prime and BA1-S boost, induced significantly higher neutralizing antibodies against pseudotyped Omicron BA1, BA2, BA2.12.1, and BA5 subvariants, and similar or higher neutralizing antibodies against the original SARS-CoV-2, than the WT-S protein alone. The WT-S/BA1-S cocktail also elicited higher or significantly higher neutralizing antibodies than the WT-S-prime-BA1-S boost, WT-S alone, or BA1-S alone against pseudotyped SARS-CoV-2 Alpha, Beta, Gamma, and Delta VOCs, and SARS-CoV, a closely related beta-coronavirus using the same receptor as SARS-CoV-2 for viral entry. By contrast, WT-S or BA1-S alone failed to induce potent neutralizing antibodies against all these viruses. Similar to the WT-S-prime-BA1-S boost, the WT-S/BA1-S cocktail completely protected mice against the lethal challenge of a Delta variant with negligible weight loss. Thus, we have identified an effective vaccination strategy that elicits potent, broadly, and durable neutralizing antibodies against circulating SARS-CoV-2 Omicron subvariants, other VOCs, original SARS-CoV-2, and SARS-CoV. These results will provide useful guidance for developing efficacious vaccines that inhibit current and future SARS-CoV-2 variants to control the COVID-19 pandemic.