Preclinical immunological evaluation of an intradermal heterologous vaccine against SARS-CoV-2 variants

Long-Term Cross Immune Response in Mice following Heterologous Prime-Boost COVID-19 Vaccination with Full-Length Spike mRNA and Recombinant S1 Protein

(1) Background: As the COVID-19 pandemic enters its fourth year, it continues to cause significant morbidity and mortality worldwide. Although various vaccines have been approved and the use of homologous or heterologous boost doses is widely promoted, the impact of vaccine antigen basis, forms, dosages, and administration routes on the duration and spectrum of vaccine-induced immunity against variants remains incompletely understood. (2) Methods: In this study, we investigated the effects of combining a full-length spike mRNA vaccine with a recombinant S1 protein vaccine, using intradermal/intramuscular, homologous/heterologous, and high/low dosage immunization strategies. (3) Results: Over a period of seven months, vaccination with a mutant recombinant S1 protein vaccine based on the full-length spike mRNA vaccine maintained a broadly stable humoral immunity against the wild-type strain, a partially attenuated but broader-spectrum immunity against variant strains, and a comparable level of cellular immunity across all tested strains. Furthermore, intradermal vaccination enhanced the heterologous boosting of the protein vaccine based on the mRNA vaccine. (4) Conclusions: This study provides valuable insights into optimizing vaccination strategies to address the ongoing challenges posed by emerging SARS-CoV-2 variants.

Preclinical safety evaluation of intradermal SARS-CoV-2 inactivated vaccine (Vero cells) administration in macaques

Coronavirus disease 2019 (COVID-19) is an acute and highly pathogenic infectious disease in humans caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Six months after immunization with the SARS-CoV-2 vaccine, however, antibodies are almost depleted. Intradermal immunization could be a new way to solve the problem of nondurable antibody responses against SARS-CoV-2 or the poor immune protection against variant strains. We evaluated the preclinical safety of a SARS-CoV-2 vaccine for intradermal immunization in rhesus monkeys. The results showed that there were no obvious abnormalities in the general clinical condition, food intake, body weight or ophthalmologic examination except for a reaction at the local vaccination site. In the hematology examination, bone marrow imaging, serum biochemistry, and routine urine testing, the related indexes of each group fluctuated to different degrees after administration, but there was no dose-response or time-response correlation. The neutralization antibody and ELISpot results also showed that strong humoral and cellular immunity could be induced after vaccination, and the levels of neutralizing antibodies increased with certain dose- and time-response trends. The results of a repeated-administration toxicity test in rhesus monkeys intradermally inoculated with a SARS-CoV-2 inactivated vaccine showed good safety and immunogenicity.

Vaccine selection for COVID-19 by AHP and novel VIKOR hybrid approach with interval type-2 fuzzy sets

Decisions in the health industry have a significant impact on human lives. With the COVID-19 pandemic, a global war is being waged. Vaccination is a critical component in this fight. The governments are attempting to offer their citizens the best vaccine for the public based on limitations. However, due to the unique characterizations of countries and the people who live in the country, the definition of "the ideal vaccination" is indefinite. Fuzzy set theory has been an ideal tool to cope with problems involving imprecise information such as the meaning of "ideal" in this case. In this study Interval Type-2 Fuzzy Sets (IT2FSs) will be used to describe uncertainty. This IT2FS structure will be the framework of the AHP (Analytic Hierarchy Process), to determine the criteria weights, and the VIKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje), to generate a set of optimal choices. The main objective of this study is to sustain the necessary effect of uncertainty of fuzzy sets via the Interval Type-2 Fuzzy (IT2F) metric to the VIKOR method and thus propose an extended VIKOR. The presented new approach will be applied to the problem of vaccine selection for COVID-19. Hence, for the first time in the literature, an application with a multilevel hierarchy will be used in IT2FAHP-VIKOR. Also, obtained optimal solution set with this hybrid framework will be compared with fuzzy AHP-VIKOR and the rankings evaluated with the IT2FTOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) and sensitivity analysis will be performed.

Evaluation of humoral immune responses induced by different SARS-CoV-2 spike trimers from wild-type and emerging variants with individual, sequential, and combinational delivered strategies

The spike trimer of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an effective target for inducing neutralizing antibodies by coronavirus disease 2019 (COVID-19) vaccines. However, the diversity of spike protein from emerging SASR-CoV-2 variants has become the major challenge for development of a universal vaccine. To investigate the immunogenicity of spike proteins from various circulating strains including wild type, Delta, and Omicron variants, we produced various natural spike trimers and designed three vaccination strategies, that is, individual, sequential, and bivalent regimens to assess autologous and heterogenous antibody responses in a mouse model. The results indicated that monovalent vaccine strategy with individual spike trimer could only induce binding and neutralizing antibodies against homologous viruses. However, sequential and bivalent immunization with Delta and Omicron spike trimers could induce significantly broader neutralizing antibody responses against heterogenous SARS-CoV-2. Interestingly, the spike trimer from Omicron variant showed superior immunogenicity in inducing antibody response against recently emerging XE variant. Taken together, our data supported the development of novel vaccination strategies or multivalent vaccine against emerging variants.

Cost-utility-safety analysis of alternative intradermal versus classical intramuscular COVID-19 vaccination

COVID-19 immunization has been shown to be effective in the prevention of COVID-19. Traditionally, two vaccination doses given by intramuscular injection are required. Many scientists present ideas for an alternative administration of COVID-19 for reducing the cost and solving the problem of insufficient COVID-19 vaccine supply. Regarding the new alternative vaccine administration, the important consideration is on cost, utility and safety. Herein, we performed cost-utility-safety analysis of alternative intradermal versus classical intramuscular COVID-19 vaccination. From cost analysis, a 80% cost reduction was derived from using intradermal COVID-19 vaccine administration comparing to intramuscular vaccination. Additional, cost-utility and cost-safety analysis also show that the cost per utility and cost per safety values for intradermal vaccination are lower than those of intramuscular vaccination. According to current research, intradermal immunization is a viable alternative to traditional intramuscular COVID-19 vaccine and may even be superior.