Routes Of Vaccine Administration Research Articles

Serologic responses to the MVA-based JYNNEOS mpox vaccine in a cohort of participants from the District of Columbia (D.C.)

We assessed early antibody responses after two doses of JYNNEOS (IMVANEX) mpox vaccine in the District of Columbia (D.C.) in persons at high risk for mpox without characteristic lesions or rash. Participants with PCR mpox negative specimens (oral swab, blood, and/or rectal swab) on the day of receipt of the first vaccine dose and who provided a baseline (day 0) serum sample and at least one serum sample at ∼28, ∼42–56 days, or 180 days post vaccination were included in this analysis. Orthopoxvirus (OPXV)-specific IgG and IgM ELISAs and neutralizing antibody titers were performed, and longitudinal serologic responses were examined. Based on participants’ IgG and IgM antibody levels at baseline, they were categorized as naïve or non-naïve. Linear mixed effects regression models were conducted to determine if IgG antibody response over time varied by age, sex, HIV status, and route of administration for both naïve and non-naïve participants. Among both naïve and non-naïve participants IgG seropositivity rates increased until day 42–56, with 89.4 % of naïve and 92.1 % of non-naïve participants having detectable IgG antibodies. The proportion of naive participants with detectable IgG antibodies declined by day 180 (67.7 %) but remained high among non-naïve participants (94.4 %). Neutralizing antibody titers displayed a similar pattern, increasing initially post vaccination but declining by day 180 among naïve participants. There were no significant serologic response differences by age, sex, or HIV status. Serologic response did vary by route of vaccine administration, with those receiving a combination of intradermal and subcutaneous doses displaying significantly higher IgG values than those receiving both doses intradermally. These analyses provide initial insights into the immunogenicity of a two-dose JYNNEOS PEP regimen in individuals at high risk of mpox exposure in the United States.

Investigation of an mpox outbreak affecting many vaccinated persons in Chicago, IL-March 2023-June 2023.

After months of few mpox cases, an increased number of cases were reported in Chicago during May 2023; predominantly among fully vaccinated patients. We investigated the outbreak scope, differences between vaccinated and unvaccinated patients, and hypotheses for monkeypox virus (MPXV) infection after vaccination. We interviewed patients and reviewed medical records to assess demographic, behavioral, and clinical characteristics, mpox vaccine status, and vaccine administration routes. We evaluated serum antibody levels after infection and compared patient viral genomes with MPXV sequences in available databases. We discussed potential vaccine compromise with partners who manufactured, handled, and administered vaccine associated with breakthrough infections. During March 18-June 27, 2023, we identified 49 mpox cases; 57% of these mpox patients were fully vaccinated (FV). FV patients received both JYNNEOS doses subcutaneously (57%), intradermally (7%), or via heterologous administration (36%). FV patients had more median sex partners (3, IQR=1-4) versus not fully vaccinated (NFV) patients (1, IQR=1-2). Thirty-six of 37 sequenced specimens belonged to lineage B.1.20 of clade IIb MPXV, which did not demonstrate any amino acid changes relative to B.1, the predominant lineage from May 2022. Vaccinated patients demonstrated expected humoral antibody responses; none were hospitalized. No vaccine storage excursions were identified. Approximately 63% of people at risk for mpox in Chicago were FV during this period. Our investigation indicated cases were likely due to frequent behaviors associated with mpox transmission, even with relatively high vaccine effectiveness and vaccine coverage. Cases after vaccination might occur in similar populations.

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.

Development of an Oral IgA Response against SARS-CoV-2 Following Immunization with Different COVID-19 Vaccines.

The mucosal immune response is recognized to be important in the early control of infection sustained by viruses with mucosal tissues as the primary site of entry and replication, such as SARS-CoV-2. Mucosal IgA has been consistently reported in the mouth and eye of SARS-CoV-2 infected subjects, where it correlated inversely with COVID-19 symptom severity. Yet, there is still scarce information on the comparative ability of the diverse SARS-CoV-2 vaccines to induce local IgA responses at the virus entry site. Thus, the aim of this study was to assess the presence of anti-SARS-CoV-2 IgA in the saliva of 95 subjects vaccinated with a booster dose and different combinations of vaccines, including mRNA-1273 (Moderna), BNT162b2 (Pfizer-BioNTech), and Vaxzevria (AstraZeneca). The results showed the presence of a mucosal response in 93.7% of vaccinated subjects, with a mean IgA titer of 351.5 ± 31.77 U/mL, strongly correlating with the serum anti-SARS-CoV-2 IgG titer (p < 0.0001). No statistically significant differences emerged between the vaccine types, although the salivary IgA titer appeared slightly higher after receiving a booster dose of the mRNA-1273 vaccine (Moderna) following two doses of BNT162b2 (Pfizer-BioNTech), compared to the other vaccine combinations. These data confirm what was previously reported at the eye level and suggest that monitoring salivary IgA may be a useful tool for driving forward vaccine design and surveillance strategies, potentially leading to novel routes of vaccine administration and boosting.

Intradermal Vaccination against Influenza with a STING-Targeted Nanoparticle Combination Adjuvant Induces Superior Cross-Protective Humoral Immunity in Swine Compared with Intranasal and Intramuscular Immunization.

The development of cross-protective vaccines against the zoonotic swine influenza A virus (swIAV), a potential pandemic-causing agent, continues to be an urgent global health concern. Commercially available vaccines provide suboptimal cross-protection against circulating subtypes of swIAV, which can lead to worldwide economic losses and poor zoonosis deterrence. The limited efficacy of current swIAV vaccines demands innovative strategies for the development of next-generation vaccines. Considering that intramuscular injection is the standard route of vaccine administration in both human and veterinary medicine, the exploration of alternative strategies, such as intradermal vaccination, presents a promising avenue for vaccinology. This investigation demonstrates the first evaluation of a direct comparison between a commercially available multivalent swIAV vaccine and monovalent whole inactivated H1N2 swine influenza vaccine, delivered by intradermal, intranasal, and intramuscular routes. The monovalent vaccines were adjuvanted with NanoST, a cationic phytoglycogen-based nanoparticle that is combined with the STING agonist ADU-S100. Upon heterologous challenge, intradermal vaccination generated a stronger cross-reactive nasal and serum antibody response in pigs compared with intranasal and intramuscular vaccination. Antibodies induced by intradermal immunization also had higher avidity compared with the other routes of vaccination. Bone marrow from intradermally and intramuscularly immunized pigs had both IgG and IgA virus-specific antibody-secreting cells. These studies reveal that NanoST is a promising adjuvant system for the intradermal administration of STING-targeted influenza vaccines.

Unconjugated Multi-Epitope Peptides Adjuvanted with ALFQ Induce Durable and Broadly Reactive Antibodies to Human and Avian Influenza Viruses.

An unconjugated composite peptide vaccine targeting multiple conserved influenza epitopes from hemagglutinin, neuraminidase, and matrix protein and formulated with a safe and highly potent adjuvant, Army Liposome formulation (ALFQ), generated broad and durable immune responses in outbred mice. The antibodies recognized specific epitopes in influenza peptides and several human, avian, and swine influenza viruses. Comparable antibody responses to influenza viruses were observed with intramuscular and intradermal routes of vaccine administration. The peptide vaccine induced cross-reactive antibodies that recognized influenza virus subtypes A/H1N1, A/H3N2, A/H5N1, B/Victoria, and B/Yamagata. In addition, immune sera neutralized seasonal and pandemic influenza strains (Group 1 and Group 2). This composite multi-epitope peptide vaccine, formulated with ALFQ and administered via intramuscular and intradermal routes, provides a high-performance supra-seasonal vaccine that would be cost-effective and easily scalable, thus moving us closer to a viable strategy for a universal influenza vaccine and pandemic preparedness.

Demographic Disparities in Mpox Vaccination Series Completion, by Route of Vaccine Administration - California, August 9, 2022-March 31, 2023.

In August 2022, the Food and Drug Administration authorized JYNNEOS vaccine (modified vaccinia Ankara vaccine, Bavarian Nordic), a 2-dose series used for the prevention of Monkeypox virus infection, to be administered via a dose-sparing intradermal route, in addition to the previously authorized subcutaneous route. The California Department of Public Health investigated whether demographic disparities in vaccination series completion varied by route of administration of the recipient's first dose. Among California residents who received their first dose during August 9, 2022-March 31, 2023, a total of 59.8% received a second dose. Series completion was highest among non-Hispanic White persons (64.1%), persons aged ≥65 years (72.6%), and adults with male sex assignment at birth (62.1%); series completion was lowest among non-Hispanic Black or African American persons (51.3%), persons aged 18-24 years (42.9%), and adults assigned female sex at birth (42.8%). When the first dose was received by subcutaneous administration, overall series completion was 58.8% compared with 60.2% when the first dose was administered intradermally. Odds of series completion across all race and ethnicity groups, persons aged 18-64 years, community health conditions, and persons assigned male sex at birth were not greater when the first dose was administered subcutaneously compared with intradermally. Intradermal use of JYNNEOS vaccine did not lower overall 2-dose series completion rates. Continued efforts are needed to ensure persons at risk for Monkeypox virus infection receive both recommended doses.

PLGA nanoparticles containing Intimin-Flagellin fusion protein for E. coli O157:H7 nano-vaccine

Escherichia coli O157:H7 is a foodborne pathogen that can lead to severe gastrointestinal diseases in humans. Vaccination is a promising strategy for preventing E. coli O157:H7 infections, which offers socio-economic benefits and provides the possibility of stimulating both humoral and cellular immune responses at systemic and mucosal sites. In this study, we developed a needle-free vaccine candidate against E. coli O157:H7 using poly(lactic-co-glycolic acid) (PLGA) nanoparticles entrapping a chimeric Intimin-Flagellin (IF) protein. The IF protein was expressed and verified using SDS-PAGE and western blot analysis, with a yield of 1/7 mg/L and a molecular weight of approximately 70 kDa. The prepared nanoparticles showed uniformly shaped spherical particles in the 200-nm range, as confirmed by SEM and DLS analysis. Three different routes of vaccine administration were used, including intranasal, oral, and subcutaneous, and the groups vaccinated with NPs protein had a higher antibody response compared to those receiving free protein. Subcutaneous administration of IF-NPs resulted in the highest level of IgG antibody titer, while oral administration of IF-NPs produced the highest amount of IgA antibody titer. Finally, all mice in the nanoparticle- intranasal and oral administered groups challenged with 100LD50 survived, while all control mice died before day 5. Based on these findings, we conclude that the PLGA-encapsulated IF protein has the potential to serve as a promising needle-free vaccine candidate against E. coli O157:H7.

Intramuscular mRNA BNT162b2 vaccine against SARS-CoV-2 induces neutralizing salivary IgA.

Intramuscularly administered vaccines stimulate robust serum neutralizing antibodies, yet they are often less competent in eliciting sustainable "sterilizing immunity" at the mucosal level. Our study uncovers a strong temporary neutralizing mucosal component of immunity, emanating from intramuscular administration of an mRNA vaccine. We show that saliva of BNT162b2 vaccinees contains temporary IgA targeting the receptor-binding domain (RBD) of severe acute respiratory syndrome coronavirus-2 spike protein and demonstrate that these IgAs mediate neutralization. RBD-targeting IgAs were found to associate with the secretory component, indicating their bona fide transcytotic origin and their polymeric multivalent nature. The mechanistic understanding of the high neutralizing activity provided by mucosal IgA, acting at the first line of defense, will advance vaccination design and surveillance principles and may point to novel treatment approaches and new routes of vaccine administration and boosting.

Tilapia Lake Virus Vaccine Development: A Review on the Recent Advances.

Tilapia tilapinevirus (or tilapia lake virus, TiLV) is a recently emerging virus associated with a novel disease affecting and decimating tilapia populations around the world. Since its initial identification, TiLV has been reported in 17 countries, often causing mortalities as high as 90% in the affected populations. To date, no therapeutics or commercial vaccines exist for TiLV disease control. Tilapia exposed to TiLV can develop protective immunity, suggesting that vaccination is achievable. Given the important role of vaccination in fish farming, several vaccine strategies are currently being explored and put forward against TiLV but, a comprehensive overview on the efficacy of these platforms is lacking. We here present these approaches in relation with previously developed fish vaccines and discuss their efficacy, vaccine administration routes, and the various factors that can impact vaccine efficacy. The overall recent advances in TiLV vaccine development show different but promising levels of protection. The field is however hampered by the lack of knowledge of the biology of TiLV, notably the function of its genes. Further research and the incorporation of several approaches including prime-boost vaccine regimens, codon optimization, or reverse vaccinology would be beneficial to increase the effectiveness of vaccines targeting TiLV and are further discussed in this review.

Effectiveness and safety of tetanus vaccine administration by intramuscular vs. subcutaneous route in anticoagulated patients: Randomized clinical trial in primary care.

Prospective, double-blind clinical trial comparing tetanus-diphtheria vaccine administration routes, intramuscular (IM) vs. subcutaneous (SC) injection, in patients with oral anticoagulants. ISRCTN69942081. Patients treated with oral anticoagulants, 15 health centers, Vigo (Spain). Sample size, 117 in each group. Safety analysis: systemic reactions and, at the vaccine administration site, erythematic, swelling, hematoma, granuloma, pain.Effectiveness analysis: differences in tetanus toxoid antibody titers.Independent variables: route, sex, age, baseline serology, number of doses administered. Following the CONSORT guidelines, we performed an intention-to-treat analysis. We conducted a descriptive study of the variables included in both groups (117 in each group) and a bivariate analysis. Fewer than 5% of missing values. Imputation in baseline and final serology with the median was performed. Lost values were assumed to be values missing at random. We conducted a descriptive study of the variables and compared routes. For safety, multivariate logistic regression was applied, with each safety criterion as outcome and the independent variables. Odds ratios (ORs) were calculated. For effectiveness, a generalized additive mixed model, with the difference between final and initial antibody titers as outcome. Due to the bimodal distribution of the outcome, the normal mixture fitting with gamlssMX was used. All statistical analyses were performed with the gamlss.mx and texreg packages of the R free software environment. A previously published protocol was used across the 6-year study period. The breakdown by sex and route showed: 102 women and 132 men; and 117 IM and 117 SC, with one dose administered in over 80% of participants. There were no differences between groups in any independent variable. The second and third doses administered were not analyzed, due to the low number of cases. In terms of safety, there were no severe general reactions. Locally, significant adjusted differences were observed: in pain, by sex (male, OR: 0.39) and route (SC, OR: 0.55); in erythema, by sex (male, OR: 0.34) and route (SC, OR: 5.21); and in swelling, by sex (male, OR: 0.37) and route (SC, OR: 2.75). In terms of effectiveness, the model selected was the one adjusted for baseline serology.

Enhancing Immunogenicity of Influenza Vaccine in the Elderly through Intradermal Vaccination: A Literature Analysis.

Aging and immunosenescence lead to a gradual decline in immune responses in the elderly and the immunogenicity of influenza vaccines in this age group is sub-optimal. Several approaches have been explored to enhance the immunogenicity of influenza vaccines in the elderly, including incorporating vaccine adjuvant, increasing antigen dosage, and changing the route of vaccine administration. We systematically compared the immunogenicity and safety of influenza vaccines administered by intradermal (ID) route and either intramuscular (IM) or subcutaneous (SC) routes in older adults aged ≥ 65. Of 17 studies included in this analysis, 3 studies compared the immunogenicity of ID vaccination to that of SC vaccination and 14 studies compared ID and IM vaccinations. ID vaccination was typically more immunogenic than both IM and SC routes at the same dosage. Importantly, a minimum of 3 µg of hemagglutinin antigen could be formulated in an ID influenza vaccine without a significant loss of immunogenicity. ID administration of standard-dose, unadjuvanted influenza vaccine was as immunogenic as IM injection of adjuvanted influenza vaccine. Waning of influenza-specific immunity was significant after 6 months, but there was no difference in waning immunity between vaccinations in ID, IM, or SC routes. While ID vaccination elicited local adverse reactions more frequently than other routes, these reactions were mild and lasted for no more than 3 days. We conclude that ID vaccination is superior to IM or SC routes and may be a suitable approach to compensate for the reduced immunogenicity observed in elderly adults. We also conclude that the main benefit of ID influenza vaccine lies in its dose-sparing effect. Additional research is still needed to further develop a more immunogenic ID influenza vaccine.

Intranasal administration of a single dose of MVA-based vaccine candidates against COVID-19 induced local and systemic immune responses and protects mice from a lethal SARS-CoV-2 infection

Current coronavirus disease-19 (COVID-19) vaccines are administered by the intramuscular route, but this vaccine administration failed to prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infection in the upper respiratory tract, mainly due to the absence of virus-specific mucosal immune responses. It is hypothesized that intranasal (IN) vaccination could induce both mucosal and systemic immune responses that blocked SARS-CoV-2 transmission and COVID-19 progression. Here, we evaluated in mice IN administration of three modified vaccinia virus Ankara (MVA)-based vaccine candidates expressing the SARS-CoV-2 spike (S) protein, either the full-length native S or a prefusion-stabilized [S(3P)] protein; SARS-CoV-2-specific immune responses and efficacy were determined after a single IN vaccine application. Results showed that in C57BL/6 mice, MVA-based vaccine candidates elicited S-specific IgG and IgA antibodies in serum and bronchoalveolar lavages, respectively, and neutralizing antibodies against parental and SARS-CoV-2 variants of concern (VoC), with MVA-S(3P) being the most immunogenic vaccine candidate. IN vaccine administration also induced polyfunctional S-specific Th1-skewed CD4+ and cytotoxic CD8+ T-cell immune responses locally (in lungs and bronchoalveolar lymph nodes) or systemically (in spleen). Remarkably, a single IN vaccine dose protected susceptible K18-hACE2 transgenic mice from morbidity and mortality caused by SARS-CoV-2 infection, with MVA-S(3P) being the most effective candidate. Infectious SARS-CoV-2 viruses were undetectable in lungs and nasal washes, correlating with high titers of S-specific IgGs and neutralizing antibodies against parental SARS-CoV-2 and several VoC. Moreover, low histopathological lung lesions and low levels of pro-inflammatory cytokines in lungs and nasal washes were detected in vaccinated animals. These results demonstrated that a single IN inoculation of our MVA-based vaccine candidates induced potent immune responses, either locally or systemically, and protected animal models from COVID-19. These results also identified an effective vaccine administration route to induce mucosal immunity that should prevent SARS-CoV-2 host-to-host transmission.

Intranasal Immunization with Liposome-Displayed Receptor-Binding Domain Induces Mucosal Immunity and Protection against SARS-CoV-2.

The global pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to efforts in developing effective vaccine approaches. Currently, approved coronavirus disease 2019 (COVID-19) vaccines are administered through an intramuscular (I.M.) route. Here, we show that the SARS-CoV-2 spike (S) glycoprotein receptor-binding domain (RBD), when displayed on immunogenic liposomes, can be intranasally (I.N.) administered, resulting in the production of antigen-specific IgA and antigen-specific cellular responses in the lungs. Following I.N. immunization, antigen-presenting cells of the lungs took up liposomes displaying the RBD. K18 human ACE2-transgenic mice that were immunized I.M or I.N with sub-microgram doses of RBD liposomes and that were then challenged with SARS-CoV-2 had a reduced viral load in the early course of infection, with I.M. achieving complete viral clearance. Nevertheless, both vaccine administration routes led to full protection against lethal viral infection, demonstrating the potential for the further exploration and optimization of I.N immunization with liposome-displayed antigen vaccines.

Systemic immune response development in Albino rats after retrograde instillation of COVID-19 vaccine to submandibular salivary gland: An experimental study

ObjectiveThis study aimed to investigate whether using the submandibular gland duct (SMD) as an alternative mucosal route for vaccine administration induced anti-COVID-19 specific immunity. Material and methodsForty rats were randomized equally into four groups; Group I: Rats did not receive any intervention. Group II: Rats were subjected to intramuscular (IM) injection of COVID-19 vaccine. Group III: Rats were subjected to ductal cannulation by retrograde instillation of sterile saline into right SMD. Group IV: Rats in this group who had 0.5 ml of COVID-19 vaccine retrogradely injected into the right SMD. Subsequently, rats were examined for anti-COVID-19 specific antibodies (IgG). Also, light microscopic observation of glandular changes and immunohistochemical staining for CD20 was performed. ResultsThe obtained results demonstrated a significant increase in anti-COVID-19 IgG levels in all rats vaccinated via intraductal immunization (group IV) compared to group II. Histologically, ectopic follicles were found within the glandular lobules of the inoculated submandibular gland (SMG) in group IV. In addition, the nearby lymph node in group IV demonstrated reactive follicle characteristics in the form of activated secondary follicles with germinal centers (GCs). Immunohistochemically, CD20 was localized in group IV in GCs of the ectopic lymphoid tissue and the nearby lymph nodes while group I, group II, and III demonstrated negative immunoreactivity. ConclusionThe immune response demonstrated by intraductal SG immunization is generally more significant than that elicited by IM inoculation of the same vaccine.

Progress towards the Elusive Mastitis Vaccines.

Mastitis is a major problem in dairy farming. Vaccine prevention of mammary bacterial infections is of particular interest in helping to deal with this issue, all the more so as antibacterial drug inputs in dairy farms must be reduced. Unfortunately, the effectiveness of current vaccines is not satisfactory. In this review, we examine the possible reasons for the current shortcomings of mastitis vaccines. Some reasons stem from the peculiarities of the mammary gland immunobiology, others from the pathogens adapted to the mammary gland niche. Infection does not induce sterilizing protection, and recurrence is common. Efficacious vaccines will have to elicit immune mechanisms different from and more effective than those induced by infection. We propose focusing our research on a few points pertaining to either the current immune knowledge or vaccinology approaches to get out of the current deadlock. A possible solution is to focus on the contribution of cell-mediated immunity to udder protection based on the interactions of T cells with the mammary epithelium. On the vaccinology side, studies on the orientation of the immune response by adjuvants, the route of vaccine administration and the delivery systems are among the keys to success.

The Route of Vaccine Administration Determines Whether Blood Neutrophils Undergo Long-Term Phenotypic Modifications.

Innate immunity modulates adaptive immunity and defines the magnitude, quality, and longevity of antigen-specific T- and B- cell immune memory. Various vaccine and administration factors influence the immune response to vaccination, including the route of vaccine delivery. We studied the dynamics of innate cell responses in blood using a preclinical model of non-human primates immunized with a live attenuated vaccinia virus, a recombinant Modified vaccinia virus Ankara (MVA) expressing a gag-pol-nef fusion of HIV-1, and mass cytometry. We previously showed that it induces a strong, early, and transient innate response, but also late phenotypic modifications of blood myeloid cells after two months when injected subcutaneously. Here, we show that the early innate effector cell responses and plasma inflammatory cytokine profiles differ between subcutaneous and intradermal vaccine injection. Additionally, we show that the intradermal administration fails to induce more highly activated/mature neutrophils long after immunization, in contrast to subcutaneous administration. Different batches of antibodies, staining protocols and generations of mass cytometers were used to generate the two datasets. Mass cytometry data were analyzed in parallel using the same analytical pipeline based on three successive clustering steps, including SPADE, and categorical heatmaps were compared using the Manhattan distance to measure the similarity between cell cluster phenotypes. Overall, we show that the vaccine per se is not sufficient for the late phenotypic modifications of innate myeloid cells, which are evocative of innate immune training. Its route of administration is also crucial, likely by influencing the early innate response, and systemic inflammation, and vaccine biodistribution.

Life Sciences Discovery and Technology Highlights

Life Sciences Discovery and Technology Highlights

Dispersion profile of a needle-free jet injection depends on the interfacial property of the medium.

Injections into or through the skin are common drug or vaccine administration routes, which can be achieved with conventional needles, microneedles, or needle-free jet injections (NFJI). Understanding the transport mechanism of these injected fluids is critical for the development of effective drug administration devices. NFJI devices are distinct from traditional injection techniques by their route and time scale, which relies on a propelled microjet with sufficient energy to penetrate the skin surface and deliver the drug into the targeted region. The injected fluid interacts with multiple skin tissue layers and interfaces, which implies that the corresponding injection profile is dependent on their mechanical properties. In this study, we address the lack of fundamental knowledge on the impact of these interfaces on the injection profiles of NFJI devices.

Sub-cutaneous Pfizer/BioNTech COVID-19 vaccine administration results in seroconversion among young adults

Route of vaccine administration plays a role in extent and quality of immunogenicity. 790 military personnel accidentally received the first of two doses of Pfizer/BioNTech mRNA anti Covid-19 vaccine using a needle intended for subcutaneous administration. A serological blood test (on day 21, prior to the second intramuscular dose) was performed, analyzing whether immunological response was elicited. 98.2% demonstrated seroconversion. IgG titers were negatively correlated with age and did not correlate with BMI. Our results could help reassure providers confronted with a similar mistake and may even imply a possibly new and effective administration route.