Intradermal Vaccination: A Potential Tool in the Battle Against the COVID-19 Pandemic?

Design and Evaluation of Synthetic Delivery Formulations for Peptide-Based Cancer Vaccines

With the recent advances in neoantigen identification, peptide-based cancer vaccines offer substantial potential in the field of immunotherapy. However, rapid clearance, low immunogenicity, and insufficient antigen-presenting cell (APC) uptake limit the efficacy of peptide-based cancer vaccines. This review explores the barriers hindering vaccine efficiency, highlights recent advancements in synthetic delivery systems, and features strategies for the key delivery steps of lymph node (LN) drainage, APC delivery, cross-presentation strategies, and adjuvant incorporation. This paper also discusses the design of preclinical studies evaluating vaccine efficiency, including vaccine administration routes and murine tumor models.

Intradermal Fractional ChAdOx1 nCoV-19 Booster Vaccine Induces Memory T Cells: A Follow-Up Study

The administration of viral vector and mRNA vaccine booster effectively induces humoral and cellular immune responses. Effector T cell responses after fractional intradermal (ID) vaccination are comparable to those after intramuscular (IM) boosters. Here, we quantified T cell responses after booster vaccination. ChAdOx1 nCoV-19 vaccination induced higher numbers of S1-specific CD8+ memory T cells, consistent with the antibody responses. Effector memory T cell phenotypes elicited by mRNA vaccination showed a similar trend to those elicited by the viral vector vaccine booster. Three months post-vaccination, cytokine responses remained detectable, confirming effector T cell responses induced by both vaccines. The ID fractional dose of ChAdOx1 nCoV-19 elicited higher effector CD8+ T cell responses than IM vaccination. This study confirmed that an ID dose-reduction vaccination strategy effectively stimulates effector memory T cell responses. ID injection could be an improved approach for effective vaccination programs.

Intramuscular versus intradermal administration for influenza vaccination in college students: A pilot study

OBJECTIVE

College student populations are considered at greater risk of contracting influenza due to their close living conditions. Despite this increased risk, college students are reluctant to obtain annual vaccination. This pilot study sought to determine perceptions of students on a college campus who received the annual influenza vaccination via an intradermal route. Participants and methods: Forty-nine college students participated in the IRB approved study. After receiving the intradermal influenza vaccination, participants completed a demographic survey and vaccination perceptions questionnaire. Results: Participants were more likely to want to have an intradermal injection in the future and reported less pain with the intradermal injection. Additionally, individuals who reported greater pain with the intramuscular injection in the past were significantly more likely to want to receive an intradermal injection in the future (p < 0.019). Conclusions: Results suggest that intradermal route of vaccination may be more appealing to the college population.

Antigen-loaded flagellate bacteria for enhanced adaptive immune response by intradermal injection

Since the skin limits the distribution of intradermal vaccines, a large number of dendritic cells in the skin cannot be fully utilized to elicit a more effective immune response. Here, we loaded the antigen to the surface of the flagellate bacteria that was modified by cationic polymer, thus creating antigen-loaded flagellate bacteria (denoted as 'FB-Ag') to overcome the skin barrier and perform the active delivery of antigen in the skin. The FB-Ag showed fast speed (∼0.2 μm s-1) and strong dendritic cell activation capabilities in the skin model in vitro. In vivo, the FB-Ag promoted the spread of antigen in the skin through active movement, increased the contact between Intradermal dendritic cells and antigen, and effectively activated the internal dendritic cells in the skin. In a mouse of pulmonary metastatic melanoma and in mice bearing subcutaneous melanoma tumor, the FB-Ag effectively increased antigen-specific therapeutic efficacy and produced long-lasting immune memory. More importantly, the FB-Ag also enhanced the level of COVID-19 specific antibodies in the serum and the number of memory B cells in the spleen of mice. The movement of antigen-loaded flagellate bacteria to overcome intradermal constraints may enhance the activation of intradermal dendritic cells, providing new ideas for developing intradermal vaccines.

Detachable-dissolvable-microneedle as a potent subunit vaccine delivery device that requires no cold-chain

Although vaccine administration by microneedles has been demonstrated, delivery reliability issues have prevented their implementation. Through an ex vivo porcine skin experiment, we show visual evidence indicating that detachable dissolvable microneedles (DDMN) can deposit cargo into the dermis with insignificant loss of cargo to the stratum corneum. Using ovalbumin (OVA), a model antigen vaccine, as a cargo, the ex vivo experiments yielded a delivery efficiency of 86.08 ± 4.16 %. At room temperature, OVA could be stabilized for up to 35 days in DDMN made from hyaluronic acid and trehalose. The DDMN matrix could improve the denaturation temperature of the OVA from around 70-120 °C to over 150 °C, as demonstrated by differential scanning calorimetric analysis. In vivo delivery of OVA antigen into the mice's skin via DDMN elicited 10 times higher specific antibody responses compared to conventional intramuscular injection. We envision DDMN as an effective, precise dosing, intradermal vaccine delivery system that may require no cold-chain, offers a dose-sparing effect, and can be administered easily.

Refining Immunogenicity through Intradermal Delivery of Outer Membrane Vesicles against Shigella flexneri in Mice

Shigellosis remains a global health concern, especially in low- and middle-income countries. Despite improvements in sanitation, the absence of a licensed vaccine for human use has prompted global health organizations to support the development of a safe and effective multivalent vaccine that is cost-effective and accessible for limited-resource regions. Outer Membrane Vesicles (OMVs) have emerged in recent years as an alternative to live attenuated or whole-inactivated vaccines due to their immunogenicity and self-adjuvating properties. Previous works have demonstrated the safety and protective capacity of OMVs against Shigella flexneri infection in mouse models when administered through mucosal or intradermal routes. However, some immunological properties, such as the cellular response or cross-protection among different Shigella strains, remained unexplored. In this study, we demonstrate that intradermal immunization of OMVs with needle-free devices recruits a high number of immune cells in the dermis, leading to a robust cellular response marked by antigen-specific cytokine release and activation of effector CD4 T cells. Additionally, functional antibodies are generated, neutralizing various Shigella serotypes, suggesting cross-protective capacity. These findings highlight the potential of OMVs as a promising vaccine platform against shigellosis and support intradermal administration as a simple and painless vaccination strategy to address this health challenge.

Fractional Dosing of Yellow Fever Live Attenuated 17D Vaccine: A Perspective

Yellow fever virus (YFV) is a mosquito-borne flavivirus that causes over 109,000 severe infections and over 51,000 deaths annually in endemic areas of sub-Saharan Africa and tropical South America. The virus has a transmission cycle involving mosquitoes and humans or non-human primates (NHPs) as the vertebrate hosts. Although yellow fever (YF) is prevented by a live attenuated vaccine (strain 17D), recent epidemics in Angola, the Democratic Republic of the Congo (DRC), and Brazil put great pressure on vaccine stockpiles. This resulted in the World Health Organization (WHO) and Pan American Health Organization (PAHO) implementing, on an emergency basis only, off-label dose-sparing techniques and policies during 2016-2018 to protect as many people in DRC and Brazil as possible from disease during unexpected large outbreaks of YF. Subsequently non-inferiority studies involving full doses compared to fractional doses indicated promising results, leading some policy-makers and scientists to consider utilizing YF vaccine fractional doses in non-emergency scenarios. Although the additional data on the immunogenicity and safety of fractional doses are promising, there are several questions and considerations that remain regarding the use of fractional doses, including differences in the initial antibody kinetics, differences in the immune response in certain populations, and durability of the immune response to fractional doses compared to full doses. Until the remaining knowledge gaps are addressed, full doses instead of fractional doses should continue to be used unless there are insufficient doses of the vaccine available to control outbreaks of YF.

Tetravalent SARS-CoV-2 S1 subunit protein vaccination elicits robust humoral and cellular immune responses in SIV-infected rhesus macaque controllers

IMPORTANCE

The study provides important insights into the immunogenicity and efficacy of a tetravalent protein subunit vaccine candidate against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The vaccine induced both humoral and cellular immune responses in nonhuman primates with controlled SIVagm infection and was able to generate Omicron variant-specific antibodies without specifically vaccinating with Omicron. These findings suggest that the tetravalent composition of the vaccine candidate could provide broad protection against multiple SARS-CoV-2 variants while minimizing the risk of immune escape and the emergence of new variants. Additionally, the use of rhesus macaques with controlled SIVsab infection may better represent vaccine immunogenicity in humans with chronic viral diseases, highlighting the importance of preclinical animal models in vaccine development. Overall, the study provides valuable information for the development and implementation of coronavirus disease 2019 vaccines, particularly for achieving global vaccine equity and addressing emerging variants.

Immunogenicity and Reactogenicity of Messenger RNA Coronavirus Disease 2019 Vaccine Booster Administered by Intradermal or Intramuscular Route in Thai Older Adults

BACKGROUND

Intradermal (ID) vaccination may alleviate COVID-19 vaccine shortages and vaccine hesitancy.

METHODS

Persons aged ≥65 years who were vaccinated with 2-dose ChAdOx1 12-24 weeks earlier were randomized to receive a booster vaccination by either ID (20 µg mRNA-1273 or 10 µg BNT162b2) or intramuscular (IM) (100 µg mRNA-1273 or 30 µg BNT162b2) route. Anti-receptor-binding domain (RBD) immunoglobulin G (IgG), neutralizing antibody (NAb), and interferon gamma (IFN-γ)-producing cells were measured at 2-4 weeks following vaccination.

RESULTS

Of 210 participants enrolled, 70.5% were female and median age was 77.5 (interquartile range, 71-84) years. Following booster dose, both ID vaccinations induced 37% lower levels of anti-RBD IgG compared with IM vaccination of the same vaccine. NAb titers against ancestral and Omicron BA.1 were highest following IM mRNA-1273 (geometric mean, 1718 and 617), followed by ID mRNA-1273 (1212 and 318), IM BNT162b2 (713 and 230), and ID BNT162b2 (587 and 148), respectively. Spike-specific IFN-γ responses were similar or higher in the ID groups compared with IM groups. ID route tended to have fewer systemic adverse events (AEs), although more local AEs were reported in the ID mRNA-1273 group.

CONCLUSIONS

Fractional ID vaccination induced lower humoral but comparable cellular immunity compared to IM and may be an alternative for older people.

CLINICAL TRIALS REGISTRATION

TCTR20220112002.

A Promising Needle-Free Pyro-Drive Jet Injector for Augmentation of Immunity by Intradermal Injection as a Physical Adjuvant

Current worldwide mRNA vaccination against SARS-CoV-2 by intramuscular injection using a needled syringe has greatly protected numerous people from COVID-19. An intramuscular injection is generally well tolerated, safer and easier to perform on a large scale, whereas the skin has the benefit of the presence of numerous immune cells, such as professional antigen-presenting dendritic cells. Therefore, intradermal injection is considered superior to intramuscular injection for the induction of protective immunity, but more proficiency is required for the injection. To improve these issues, several different types of more versatile jet injectors have been developed to deliver DNAs, proteins or drugs by high jet velocity through the skin without a needle. Among them, a new needle-free pyro-drive jet injector has a unique characteristic that utilizes gunpower as a mechanical driving force, in particular, bi-phasic pyrotechnics to provoke high jet velocity and consequently the wide dispersion of the injected DNA solution in the skin. A significant amount of evidence has revealed that it is highly effective as a vaccinating tool to induce potent protective cellular and humoral immunity against cancers and infectious diseases. This is presumably explained by the fact that shear stress generated by the high jet velocity facilitates the uptake of DNA in the cells and, consequently, its protein expression. The shear stress also possibly elicits danger signals which, together with the plasmid DNA, subsequently induces the activation of innate immunity including dendritic cell maturation, leading to the establishment of adaptive immunity. This review summarizes the recent advances in needle-free jet injectors to augment the cellular and humoral immunity by intradermal injection and the possible mechanism of action.

The immunological effects of intradermal particle-based vaccine delivery using a novel microinjection needle studied in a human skin explant model

For intradermal (ID) immunisation, novel needle-based delivery systems have been proposed as a better alternative to the Mantoux method. However, the penetration depth of needles in the human skin and its effect on immune cells residing in the different layers of the skin has not been analyzed. A novel and user-friendly silicon microinjection needle (Bella-mu^TM) has been developed, which allows for a perpendicular injection due to its short needle length (1.4-1.8 mm) and ultrashort bevel. We aimed to characterize the performance of this microinjection needle in the context of the delivery of a particle-based outer membrane vesicle (OMV) vaccine using an ex vivo human skin explant model. We compared the needles of 1.4 and 1.8 mm with the conventional Mantoux method to investigate the depth of vaccine injection and the capacity of the skin antigen-presenting cell (APC) to phagocytose the OMVs. The 1.4 mm needle deposited the antigen closer to the epidermis than the 1.8 mm needle or the Mantoux method. Consequently, activation of epidermal Langerhans cells was significantly higher as determined by dendrite shortening. We found that five different subsets of dermal APCs are able to phagocytose the OMV vaccine, irrespective of the device or injection method. ID delivery using the 1.4 mm needle of a OMV-based vaccine allowed epidermal and dermal APC targeting, with superior activation of Langerhans cells. This study indicates that the use of a microinjection needle improves the delivery of vaccines in the human skin.

Tetravalent SARS-CoV-2 S1 Subunit Protein Vaccination Elicits Robust Humoral and Cellular Immune Responses in SIV-Infected Rhesus Macaque Controllers

The COVID-19 pandemic has highlighted the need for safe and effective vaccines to be rapidly developed and distributed worldwide, especially considering the emergence of new SARS-CoV-2 variants. Protein subunit vaccines have emerged as a promising approach due to their proven safety record and ability to elicit robust immune responses. In this study, we evaluated the immunogenicity and efficacy of an adjuvanted tetravalent S1 subunit protein COVID-19 vaccine candidate composed of the Wuhan, B.1.1.7 variant, B.1.351 variant, and P.1 variant spike proteins in a nonhuman primate model with controlled SIVsab infection. The vaccine candidate induced both humoral and cellular immune responses, with T- and B cell responses mainly peaking post-boost immunization. The vaccine also elicited neutralizing and cross-reactive antibodies, ACE2 blocking antibodies, and T-cell responses, including spike specific CD4+ T cells. Importantly, the vaccine candidate was able to generate Omicron variant spike binding and ACE2 blocking antibodies without specifically vaccinating with Omicron, suggesting potential broad protection against emerging variants. The tetravalent composition of the vaccine candidate has significant implications for COVID-19 vaccine development and implementation, providing broad antibody responses against numerous SARS-CoV-2 variants.

Immunogenicity and reactogenicity of accelerated regimens of fractional intradermal COVID-19 vaccinations

Introduction

This phase I study explored the immunogenicity and reactogenicity of accelerated, Q7 fractional, intradermal vaccination regimens for COVID-19.

Methods

Participants (n = 60) aged 18-60 years, naïve to SARS-CoV-2 infection or vaccination, were randomly allocated into one of four homologous or heterologous accelerated two-dose, two-injection intradermal regimens seven days apart:(1) BNT162b2-BNT162b2(n= 20),(2) ChAdOx1- BNT162b2 (n = 20), (3) CoronaVac-ChAdOx1 (n = 10), and (4) ChAdOx1-ChAdOx1 (n = 10). CoronaVac and ChAdOx1 were 20%, and BNT162b2 17%, of their standard intramuscular doses (0.1 mL and 0.05 mL per injection, respectively). Humoral immune responses were measured through IgG response towards receptor binding domains (RBD-IgG) of ancestral SARS-CoV-2 spike protein and pseudovirus neutralization tests (PVNT50). Cellular immune responses were measured using ELISpot for ancestral protein pools.

Results

Immunogenicity was highest in regimen (2), followed by (1), (4), and (3) 2 weeks after the second dose (P < 0.001 for anti-RBD-IgG and P= 0.01 for PVNT50). Each group had significantly lower anti-RBD IgG (by factors of 5.4, 3.6, 11.6, and 2.0 for regimens (1) to (4), respectively) compared to their respective standard intramuscular regimens (P < 0.001 for each). Seroconversion rates for PVNT50 against the ancestral strain were 75%, 90%, 57% and 37% for regimens (1) to (4), respectively. All participants elicited ELISpot response to S-protein after vaccination. Adverse events were reportedly mild or moderate across cohorts.

Discussion

We concluded that accelerated, fractional, heterologous or homologous intradermal vaccination regimens of BNT162b2 and ChAdOx1 were well tolerated, provided rapid immune priming against SARS-CoV-2, and may prove useful for containing future outbreaks.

Induction of potent antitumor immunity by intradermal DNA injection using a novel needle-free pyro-drive jet injector

The current success of mRNA vaccines against COVID-19 has highlighted the effectiveness of mRNA and DNA vaccinations. Recently, we demonstrated that a novel needle-free pyro-drive jet injector (PJI) effectively delivers plasmid DNA into the skin, resulting in protein expression higher than that achieved with a needle syringe. Here, we used ovalbumin (OVA) as a model antigen to investigate the potential of the PJI for vaccination against cancers. Intradermal injection of OVA-expression plasmid DNA into mice using the PJI, but not a needle syringe, rapidly and greatly augmented OVA-specific CD8⁺ T-cell expansion in lymph node cells. Increased mRNA expression of both interferon-γ and interleukin-4 and an enhanced proliferative response of OVA-specific CD8⁺ T cells, with fewer CD4⁺ T cells, were also observed. OVA-specific in vivo killing of the target cells and OVA-specific antibody production of both the IgG2a and IgG1 antibody subclasses were greatly augmented. Intradermal injection of OVA-expression plasmid DNA using the PJI showed stronger prophylactic and therapeutic effects against the progression of transplantable OVA-expressing E.G7-OVA tumor cells. Even compared with the most frequently used adjuvants, complete Freund's adjuvant and aluminum hydroxide with OVA protein, intradermal injection of OVA-expression plasmid DNA using the PJI showed a stronger CTL-dependent prophylactic effect. These results suggest that the novel needle-free PJI is a promising tool for DNA vaccination, inducing both a prophylactic and a therapeutic effect against cancers, because of prompt and strong generation of OVA-specific CTLs and subsequently enhanced production of both the IgG2a and IgG1 antibody subclasses.

Safety and immunogenicity of intradermal administration of fractional dose CoronaVac®, ChAdOx1 nCoV-19 and BNT162b2 as primary series vaccination

There is a limited supply of COVID-19 vaccines, with less than 20% of eligible populations in low-income countries having received one dose. Intradermal delivery of fractional dose vaccines is one way to improve global vaccine access, but no studies have reported data on intradermal delivery of COVID-19 primary series vaccination. We conducted a pilot study to examine the safety and immunogenicity of three intradermal primary series regimens – heterologous regimen of CoronaVac and ChAdOx1 (CoronaVac-ChAdOx1), homologous regimen of ChAdOx1 (ChAdOx1-ChAdOx1), and homologous regimen of BNT162b2 (BNT162b2-BNT162b2). Each dose was 1/5^th or 1/6^th of the standard dose. Two additional exploratory arms of intradermal vaccination for the second dose following an intramuscular first dose of ChAdOx1 and BNT162b2 were included. Intradermal vaccination was found to be immunogenic and safe. The antibody responses generated by the intradermal primary series were highest in the BNT162b2 arms. The anti-receptor binding domain (anti-RBD) IgG concentration following fractional dose intradermal vaccination was similar to that of standard dose intramuscular vaccination of the same regimen for all study arms except for BNT162b2. The BNT162b2 intradermal series generated a lower antibody concentration than the reference intramuscular series, despite generating the highest antibody concentration of all three intradermal primary series regimens. Neutralizing antibody responses against the SARS-CoV-2 ancestral strain were consistent with what was observed for anti-RBD IgG, with lower titers for SARS-CoV-2 variants. Neutralizing titers were lowest against the omicron variant, being undetectable in about a quarter of study participants. T-cell responses against spike- and nucleocapsid-membrane-open reading frame proteins were also detected following intradermal vaccination. Adverse effects following intradermal vaccination were generally comparable with post-intramuscular vaccination effects. Taken together, our data suggest that intradermal vaccination using 1/5^th or 1/6^th of standard COVID-19 intramuscular vaccination dosing were immunogenic with tendency of lower systemic adverse reactions than intramuscular vaccination. Our findings have implications in settings where COVID-19 vaccines are in shortage.

Does an Intradermal Vaccination for Monkeypox Make Sense?

Mankind has recently had to deal a series of virus-mediated pandemics, resulting in extensive morbidity and mortality rates that have severely strained healthcare systems. While dealing with viral infections as a healthcare concern is not new, our exceptionally mobile society has added to the critical challenge of limiting pathogen spread of a highly transmissible virus prior to the generation, testing, and distribution of safe and effective vaccines. The tremendous global effort put forth to address the recent pandemic induced by SARS-CoV-2 infection has highlighted many of the strengths and weaknesses of how vaccines are identified, tested, and used to provide protection. These uncertainties are exacerbated by the lack of clear and consistent messaging that can occur when the processes of research, development, and clinical testing that normally requires years of study and consideration are compressed into a few months. In this commentary, I will provide some background on the intramuscular (IM), subcutaneous (SC), and intradermal (ID) administration routes used for injectable vaccines and some information on potential immunological outcomes. With this background, I will address the recent FDA decision to allow an approved vaccine against monkeypox virus to be administered by ID, as well as its initial approval route via SC, injection as a dose-sparing strategy to maximize immunization numbers using current stockpiles.

Intradermal Allergen Immunotherapy for Allergic Rhinitis: Current Evidence

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated inflammatory disease that is induced by allergen introduction to the nasal mucosa, which triggers an inflammatory response. The current treatments for AR include allergen avoidance and pharmacotherapy; however, allergen-specific immunotherapy (AIT) is the only treatment that can be employed to modify immunologic responses and to achieve a cure for allergic diseases. The current standard routes of AIT administration are the subcutaneous and sublingual routes. Alternatively, the dermis contains a high density of dermal dendritic cells that act as antigen-presenting cells, so intradermal administration may confer added advantages and increase the efficacy of AIT. Moreover, intradermal immunotherapy (IDIT) may facilitate a reduction in the allergen dosage and a shortening of the treatment duration. The aim of this review was to search and evaluate the current evidence specific to IDIT, including its modified formulations, such as allergoids and peptides. The results of this review reveal conflicting evidence that suggests that the overall benefit of IDIT remains unclear. As such, further clinical trials are needed to establish the clinical utility of IDIT, and to determine the optimal treatment-related protocols.

OC, Mohana Borges RDS, Tanuri A, Souza TML, Rossi-Bergmann B, Vale AM, Silva JL, de Oliveira AC, Filardy AD, Gomes AMO, de Matos Guedes HL. Immunogenicity of SARS-CoV-2 Trimeric Spike Protein Associated to Poly(I:C) Plus Alum

The SARS-CoV-2 pandemic has had a social and economic impact worldwide, and vaccination is an efficient strategy for diminishing those damages. New adjuvant formulations are required for the high vaccine demands, especially adjuvant formulations that induce a Th1 phenotype. Herein we assess a vaccination strategy using a combination of Alum and polyinosinic:polycytidylic acid [Poly(I:C)] adjuvants plus the SARS-CoV-2 spike protein in a prefusion trimeric conformation by an intradermal (ID) route. We found high levels of IgG anti-spike antibodies in the serum by enzyme linked immunosorbent assay (ELISA) and high neutralizing titers against SARS-CoV-2 in vitro by neutralization assay, after two or three immunizations. By evaluating the production of IgG subtypes, as expected, we found that formulations containing Poly(I:C) induced IgG2a whereas Alum did not. The combination of these two adjuvants induced high levels of both IgG1 and IgG2a. In addition, cellular immune responses of CD4⁺ and CD8⁺ T cells producing interferon-gamma were equivalent, demonstrating that the Alum + Poly(I:C) combination supported a Th1 profile. Based on the high neutralizing titers, we evaluated B cells in the germinal centers, which are specific for receptor-binding domain (RBD) and spike, and observed that more positive B cells were induced upon the Alum + Poly(I:C) combination. Moreover, these B cells produced antibodies against both RBD and non-RBD sites. We also studied the impact of this vaccination preparation [spike protein with Alum + Poly(I:C)] in the lungs of mice challenged with inactivated SARS-CoV-2 virus. We found a production of IgG, but not IgA, and a reduction in neutrophil recruitment in the bronchoalveolar lavage fluid (BALF) of mice, suggesting that our immunization scheme reduced lung inflammation. Altogether, our data suggest that Alum and Poly(I:C) together is a possible adjuvant combination for vaccines against SARS-CoV-2 by the intradermal route.

Immunogenicity and reactogenicity after booster dose with AZD1222 via intradermal route among adult who had received CoronaVac

BACKGROUND

Currently, booster dose is needed after 2 doses of non-live COVID-19 vaccine. With limited resources and shortage of COVID-19 vaccines, intradermal(ID) administration might be a potential dose-sparing strategy.

OBJECTIVE

To determine immunologic response and reactogenicity of ID ChAdOx1 nCoV-19 vaccine (AZD1222,Oxford/AstraZeneca) as a booster dose after completion of 2-dose CoronaVac(SV) in healthy adult.

METHODS

This is a prospective cohort study of adult aged 18-59 years who received 2-dose SV at 14-35 days apart for more than 2 months. Participants received ID AZD1222 at fractional low dose(1×10¹⁰ viral particles,0.1 ml). Antibody responses were evaluated by surrogate virus neutralization test(sVNT) against delta variant and wild type, and anti-spike-receptor-binding-domain immunoglobulin G(anti-S-RBD IgG) at prior, day14, 28, 90, and 180 post booster. Solicited reactogenicity was collected for 7 days post-booster. Primary endpoint was the differences of sVNT against delta strain ≥ 80% inhibition at day14 and 90 compared with the parallel cohort study of 0.5-ml intramuscular(IM) route.

RESULTS

From August2021, 100 adults with median age of 46 years(IQR 41-52) participated. Prior to booster, geometric mean(GM) of sVNT against delta strain was 22.4% inhibition(95 %CI 18.7-26.9) and of anti-S-RBD IgG was 109.3 BAU/ml(95.4-125.1). Post ID booster, GMs of sVNT against delta strain were 95.5% inhibition (95%CI 94.2-96.8) at day14, 73.1% inhibition (66.7-80.2) at day90, and 22.7% inhibition (14.9-34.6) at day180. The differences of proportion of participants achieving sVNT against delta strain ≥ 80% inhibition in ID recipients versus IM were + 4.2% (95 %CI -2.0to10.5) at day14, and -37.3%(-54.2to-20.3) at day90. Anti-S-RBD IgG GMs were 2037.1 BAU/ml (95%CI 1770.9-2343.2) at day14 and 744.6 BAU/ml(650.1-852.9) at day90, respectively. Geometric mean ratios(GMRs) of anti-S-RBD IgG were 0.99(0.83-1.20) at day14, and 0.82(0.66-1.02) at day90. Only 18% reported feverish, compared with 37% of IM (p = 0.003). Common reactogenicity was erythema at injection site(53%) while 7% reported blister.

CONCLUSION

Low-dose ID AZD1222 booster enhanced lower neutralizing antibodies at 3 months compared with IM route. Less systemic reactogenicity occurred, but higher local reactogenicity.

Immunogenicity and safety of an intradermal ChAdOx1 nCoV-19 boost in a healthy population

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic. Two doses of an inactivated SARS-CoV-2 vaccine (CoronaVac) have been shown to be insufficient to protect against variants of concern (VOCs), while viral vector vaccines remain protective against the infection. Herein, we conducted a preliminary study to evaluate the safety and immunity in an adult population who received the conventional 2 dosage-regimen of inactivated SARS-CoV-2 vaccine; with an additional intradermal ChAdOx1 nCoV-19 reciprocal dosage (1:5). An Intramuscular ChAdOx1 nCoV-19 booster was also included as a control. Immediate and delayed local reactions were frequently observed in the fractional intradermal boost, but systemic side effects were significantly decreased compared to the conventional intramuscular boost. The anti-RBD-IgG levels, the neutralising function against delta variants, and T cell responses were significantly increased after boosting via both routes. Interestingly, the shorter interval elicited higher immunogenicity compared to the extended interval. Taken together, a reciprocal dosage of intradermal ChAdOx1 nCoV-19 booster reduces systemic adverse reactions and enhances non inferiority humoral and cellular immune responses compared to a full dose of intramuscular boosting. These findings provide for an effective vaccine management during the shortages of vaccine supply.

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.

Safety, tolerability, and antibody response after intradermal vaccination of PFE-BNT in adults who have completed two-doses of Verocell (inactivated vaccine)

Introduction

The necessity for an equal distribution of the COVID-19 vaccination is critical. Lower-middle and lower income countries may not be able to manufacture their vaccines, nor may they be able to afford to buy them for every inhabitant. Furthermore, the vaccination's potency may wane over time. A booster dosage is recommended. Despite this, certain areas or groups of people are still waiting for their first vaccine dosage.

Objectives

The purposes of this study were to assess the safety and tolerability of patients who received a fractionated intradermal administration (ID) of PFE-BNT as a booster dose in a group of people who had previously finished full doses of Verocell and to determine the antibody response after the injection.

Methods

An open-label experiment was carried out. Participants were at least 18 years old. Participants received 6 ug of PFE-BNT vaccination through intradermal injection. The safety and adverse reactions were monitored at immediate after injection, 30 min later, day 1, day 7, and day 30. Venous blood tests for specific IgG concentration against SARS-CoV-2 spike S1 were received prior to injection and day 30.

Results

42 participants completed the study. The mean age was 48 (the range; 23–62). The average duration after completing the 2nd dose of Verocell was 78.3 days (95% CI; 73.9–82.8). There was no serious adverse event. Almost 50% of participants reported minor adverse reactions on day 1 and roughly 30% still reporting on day 7. Systemic reactions were found less than 5%. The antibody level at day 30 was 16669.8 (95% CI; 3692.6–51238.9), which was 40 times higher.

Conclusion

PFE-BNT at a dose of 6 ug (1/5 of the typical dose) was shown to be safe and well tolerated when given intradermally. The antibody reaction was very strong. The ID administration could potentially save vaccine doses.

Immunogenicity and Safety of an Intradermal BNT162b2 mRNA Vaccine Booster after Two Doses of Inactivated SARS-CoV-2 Vaccine in Healthy Population

Effective vaccine coverage is urgently needed to tackle the COVID-19 pandemic. Inactivated vaccines have been introduced in many countries for emergency usage, but have only provided limited protection. Heterologous vaccination is a promising strategy to maximise vaccine immunogenicity. Here, we conducted a phase I, randomised control trial to observe the safety and immunogenicity after an intradermal boost, using a fractional dosage (1:5) of BNT162b2 mRNA vaccine in healthy participants in Songkhla, Thailand. In total, 91 volunteers who had been administered with two doses of inactivated SARS-CoV-2 (CoronaVac) were recruited into the study, and then randomised (1:1:1) to received different regimens of the third dose. An intramuscular booster with a full dose of BNT162b2 was included as a conventional control, and a half dose group was included as reciprocal comparator. Both, immediate and delayed adverse events following immunisation (AEFI) were monitored. Humoral and cellular immune responses were examined to observe the booster effects. The intradermal booster provided significantly fewer systemic side effects, from 70% down to 19.4% (p < 0.001); however, they were comparable to local reactions with the conventional intramuscular booster. In the intradermal group after receiving only one fifth of the conventional dosage, serum Anti-RBD IgG was halved compared to the full dose of an intramuscular injection. However, the neutralising function against the Delta strain remained intact. T cell responses were also less effective in the intradermal group compared to the intramuscular booster. Together, the intradermal booster, using a fractional dose of BNT162b2, can reduce systemic reactions and provides a good level and function of antibody responses compared to the conventional booster. This favourable intradermal boosting strategy provides a suitable alternative for vaccines and effective vaccine management to increase the coverage during the vaccine shortage.

Intradermal ChAdOx1 Vaccine Following Two CoronaVac Shots: A Case Report

Inactivated SARS-CoV-2 vaccines are used in many countries with uncertain immunogenicity. Intradermal ChAdOx1 has been proposed as a resource-efficient heterologous third booster shot. A 52-year-old healthy male healthcare professional had received two intramuscular CoronaVac shots on 21 April and 23 May 2021, and volunteered to take a 0.1 mL ChAdOx1 vaccine intradermally on 29 June 2021, with minimal local reactions. The declining IgG levels against spike protein from the two CoronaVac shots increased to higher than 10,000 AU/mL two weeks after the intradermal ChAdOx1. Moreover, the neutralizing antibody increased from 66.77% to almost 100%. A ratio of 6.6:9.7 of IgA:IgG was observed. The 50% pseudovirus neutralization titer (PVNT50) against lentiviral pseudovirus bearing a codon-optimized spike gene (wild type, alpha, beta, and delta) were 1812.42, 822.99, 1025.42, 1347.13, respectively. The SARS-CoV-2-specific T cells to spike protein-peptide pools (532-788 SFU/106 PBMCs) were detected. In conclusion, the antibody and cellular responses to the intradermal ChAdOx1, as a third booster dose in a healthy volunteer who received two intramuscular CoronaVac shots, revealed a dramatic increase in the total antibodies, including IgG, IgA, as well as T cell responses against spike protein. The immune response from intradermal ChAdOx1 should be further investigated in a larger population.

An Update on mRNA-Based Viral Vaccines

With the success of COVID-19 vaccines, newly created mRNA vaccines against other infectious diseases are beginning to emerge. Here, we review the structural elements required for designing mRNA vaccine constructs for effective in vitro synthetic transcription reactions. The unprecedently speedy development of mRNA vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was enabled with previous innovations in nucleoside modifications during in vitro transcription and lipid nanoparticle delivery materials of mRNA. Recent updates are briefly described in the status of mRNA vaccines against SARS-CoV-2, influenza virus, and other viral pathogens. Unique features of mRNA vaccine platforms and future perspectives are discussed.

A Call to Action by the Italian Mesotherapy Society on Scientific Research

Mesotherapy (local intradermal therapy, LIT) is a technique used to slowly spread drugs in tissues underlying the site of injection to prolong the pharmacological effect with respect to intramuscular injection. Recommendations for proper medical use of this technique have been made for pain medicine and rehabilitation, chronic venous disease, sport medicine, musculoskeletal disorders, several dermatological conditions, skin ageing, and immune-prophylaxis. Although mesotherapy is considered a valid technique, unresolved questions remain, which should be answered to standardize methodology and dosing regimen as well as to define the right indications in clinical practice. New randomized controlled trials are needed to test single products (dose, frequency of administration, efficacy and safety). Even infiltration of substances for dermo-cosmetic purposes must be guided by safety and efficacy tests before being proposed by mesotherapy. In this article, we put forth a preclinical and clinical research plan and a health technology assessment as a call to action by doctors, researchers and scientific societies to aid national health authorities in considering mesotherapy for prevention, treatment and rehabilitation paths.