Search Results (475)

Background: In 2019, a new virus caused by SARS-CoV-2, called COVID-19, spread throughout the world, causing a pandemic state. As the pandemic progressed and cases continued to increase, safe vaccines were developed for the entire population. In Brazil, AstraZeneca^® (ChAdOx1-S) and Pfizer^® (BNT162b2) vaccines were among those administered to the population. Objectives: The objective of this study was to analyze whether immunoglobulin G (IgG) is produced for COVID-19 in individuals immunized with two doses of AstraZeneca (ChAdOx1-S) and Pfizer (BNT162b2) vaccines and to evaluate several parameters in order to understand how our bodies respond to this immunization. Methods: The study involved the participation of 120 individuals: 49 in the control group, 44 vaccinated with the AstraZeneca vaccine, and 27 the vaccinated with Pfizer vaccine. Results: Hematological, biochemical, inflammatory, and oxidant/antioxidant parameters and the production of IgG antibodies were analyzed. An increase in some inflammatory parameters was observed in vaccinated individuals, which may have been caused by an immune reaction after vaccination. In terms of hematological parameters, the changes caused by vaccination appear to be transient and quickly resolved after immunization. In terms of biochemical parameters, an increase in IgG antibodies was observed in the group vaccinated with the Pfizer^® vaccine; however, the AstraZeneca^® and control groups also produced IgG, although to a lesser extent. In terms of the remaining parameters, there was little change after vaccination. Regarding the levels of oxidants/antioxidants, it was observed that there was a compensation by antioxidants due to the increase in oxidant parameters, which may act as corrective mechanism. Conclusions: Both the AstraZeneca^® and Pfizer^® vaccines induced anti-SARS-CoV-2 IgG production, accompanied by inflammatory, hematological, and oxidative changes. Full article

Background/Objectives: Paediatricians’ recommendations influence parental decisions to vaccinate their children. On 19 January 2022, the World Health Organization authorized the Pfizer-BioNTech COVID-19 vaccine (BNT162b2) under Emergency Use Listing for children under 12 years as a measure to mitigate disease spread and direct protection for children with underlying conditions. We assessed knowledge, attitudes, and practices (KAP) of Palestinian paediatricians regarding COVID-19 vaccination for children under 12 years and identified factors affecting support for vaccination. Methods: From 1 October to 8 November 2023, we surveyed paediatricians across the West Bank using structured telephone interviews. We collected data on sociodemographic characteristics and KAP regarding COVID-19 vaccination and calculated KAP scores from eight, nine, and nine items, respectively, with total scores categorized as poor/moderate/good. We performed bivariable and multivariable analyses to identify factors associated with paediatricians supporting COVID-19 vaccination for children under 12 years. Results: Of the 367 eligible paediatricians, 323 (88%) responded; the median age was 51 years (range: 28–70); 27% supported COVID-19 vaccination for children. Mean scores for knowledge (range 0–8), attitude (0–9), and practice (0–9) were 3.0 ± 2.1, 3.9 ± 2.4, and 4.0 ± 1.7, respectively. The mean overall KAP score (0–26) was 11 ± 4.8. Safety and efficacy concerns and lack of long-term data were the main reasons for hesitancy. Higher knowledge scores (PR = 1.8, 95% CI: 1.3–2.5, p = 0.001) and positive attitudes (PR = 1.6, 95% CI: 1.1–2.3, p = 0.01) were significantly associated with paediatricians’ support for vaccination. After adjustment for other factors, participants with regular continuing medical education attendance (aPR = 1.4, 95% CI: 1.0–2.6, p = 0.045), trusting WHO recommendations (aPR = 3.1, 95% CI: 1.4–7.8, p = 0.047), having a positive attitude score (aPR = 1.3, 95% CI: 0.4–4.4, p = 0.041), and a good total KAP score (aPR = 1.1, 95% CI: 1.0–1.2, p = 0.044) supported COVID-19 vaccination for children. Conclusions: Support for COVID-19 vaccination among Palestinian paediatricians was low, associated with their knowledge, attitudes, and trust in health authorities. The revised WHO recommendations from 10 November 2023, decreasing the priority of vaccinating healthy children, could influence the opinion of paediatricians. However, the low support for COVID-19 vaccinations could affect the performance of other vaccination programmes and should be carefully addressed through targeted education. Full article

To contrast the COVID-19 pandemic brought by the corona virus SARS-CoV-2, two mRNA-based anti-COVID-19 vaccines (by Pfizer-BioNTech and Moderna) were made available relatively quickly and deployed worldwide based on an emergency approval. Being considered vulnerable and at risk of infection, cancer patients have been prioritized for COVID-19 vaccination and vaccinated repeatedly because of the short time protection provided by these vaccines. Recently, a surge in the incidence and rapid progression of cancers has been observed in many countries, which could (at least partially) represent cancers undiagnosed or untreated during the pandemic. It has also been suggested that the SARS-CoV-2 itself or even the anti-COVID-19 mRNA vaccines could have contributed to the recurrence and worse clinical outcome in cancer patients, given the high incidence of COVID-19 in hospitalized patients and that these patients have been vaccinated with priority several times and in a short period. Although it appears extremely unlikely that SARS-CoV-2 and anti-COVID-19 mRNA vaccines elicit genotoxic events and cause neo-cancerogenesis in a short time, they could still cause non-genotoxic pro-carcinogenic effects by triggering an exaggerated inflammatory reaction, compromising immune homeostasis, stimulating cell proliferation, and negatively affecting cellular stress response and damage repair machinery. This could result in the promotion of regrowth of dormant micrometastases or relapses of stable minimal residual disease. Such a harmful outcome may likely result from a synergy between the virus and the vaccine, especially in multi-vaccinated and multi-infected individuals. Here, I bring the cell pathologist’s point of view and discuss the multiple possible mechanisms by which the virus and the anti-COVID-19 mRNA vaccine might favor tumorigenesis. While a causal link cannot be established at this stage, knowledge of potential carcinogenic risks could help doctors and health policymakers take the best actions to protect vulnerable patients and convince the vaccine developer to design a vaccine free from such harm. Full article

Background and Clinical Significance: This case report describes a 46-year-old male with no prior comorbidities who developed progressive neurological symptoms—ataxia and diplopia—shortly after the second Comirnaty (Pfizer-BioNTech) COVID-19 vaccine dose. The aim is to highlight the diagnostic challenges of central nervous system-dominant hemophagocytic lymphohistiocytosis (HLH) and its overlap with neuroinflammatory disorders. Case Presentation: Initial MRI showed demyelinating lesions in the brain and spinal cord, suggesting acute disseminated encephalomyelitis (ADEM). The patient had only transient improvement with corticosteroids and then multiple relapses with expanding CNS lesions despite cyclophosphamide, plasmapheresis, and rituximab. After 27 months, systemic features appeared, including fever, cytopenias, elevated inflammatory markers, and splenomegaly. Bone marrow analysis revealed hemophagocytosis, fulfilling HLH-2004 criteria, with an H-score of 200 supporting secondary HLH. Given consanguinity and persistent immune activation, next-generation sequencing identified two homozygous PRF1 variants—one pathogenic (p.Arg232His) and one of uncertain significance (p.Ala91Val)—consistent with autosomal recessive familial type 2 HLH. The patient underwent matched unrelated donor hematopoietic stem cell transplantation (HSCT) 11 months after HLH diagnosis, achieving initial stabilization, but ultimately died from infectious complications in March 2025 without evidence of HLH relapse. Conclusions: This case illustrates an atypical adult-onset presentation of familial HLH manifesting primarily with recurrent neuroinflammatory symptoms that initially mimicked ADEM. The diagnostic delay reflects the challenge of recognizing CNS-dominant HLH, especially in adults and in the absence of early systemic features. The identification of biallelic PRF1 variants confirmed an underlying genetic predisposition. This is the first reported case of adult-onset familial HLH presenting predominantly with neurological symptoms following COVID-19 vaccination. The case emphasizes the need to consider genetic forms of HLH in relapsing neuroinflammatory disorders and raises the hypothesis that vaccination may unmask subclinical immune dysregulation in genetically susceptible individuals Full article

Background/Objectives: Following the global spread of SARS-CoV-2, there was an urgent need for vaccine development to support immune protection. This study aimed to evaluate the impact of active and hybrid immunity on the durability of immunoglobulin G (IgG), neutralizing antibodies, and cellular immune responses over a two-year period. Methods: This longitudinal study was conducted from February 2021 to December 2023 at the Public Health Institute in Ostrava, Czech Republic. Anti-S IgG was measured using ELISA (Euroimmun), neutralizing antibodies via an in-house virus neustralization test (VNT), and cellular immune response using the IGRA test (ELISA, Euroimmun). Participants also completed a questionnaire on demographics, COVID-19 history, symptoms, and vaccination. Statistical analysis included descriptive and non-parametric tests (Mann–Whitney U, Kruskal–Wallis) at a 5% significance level. Results: The cohort included 149 individuals, 97.3% of whom were vaccinated with Comirnaty (Pfizer/BioNTech). A total of 17% had confirmed infection prior to vaccination and showed up to two-fold higher neutralizing antibody levels (p < 0.001) within 2–6 weeks postvaccination. Postvaccination infection was reported in 35% of participants. Although antibody levels declined over the 2–100 week period, participants remained seropositive across all three parameters. Cellular immune response (interferon-γ) remained consistently high throughout follow-up. Conclusions: The study demonstrates long-term durability of IgG and neutralizing antibodies and confirms durable cellular immunity up to two years postvaccination. Hybrid immunity significantly enhanced neutralizing antibody levels, supporting its added value in protective immunity against SARS-CoV-2. Full article

Background: Numerous studies have proved the efficacy of vaccination in reducing Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) transmission and the coronavirus disease (COVID-19) burden. However, even though the COVID-19 vaccination coverage is high for primary doses, a booster dose is needed to sustain protection. Continuing our previous research, this study evaluates the immunogenicity and safety of full and half doses of two COVID-19 booster vaccines, ChAdOx1-S (AstraZeneca) and BNT162b2 (Pfizer-BioNTech), in individuals primed with ChAdOx1-S. Methods: This study was an observer-blind randomized controlled trial to evaluate the immunogenicity and safety of half and full doses of two COVID-19 booster vaccine types, BNT162b2 and ChAdOx1-S, among fully vaccinated, ChAdOx1-S-primed individuals in Jakarta, Indonesia. A total of 329 participants were randomized to receive either full or half doses of the booster vaccines, namely the ChAdOx1-S and BNT162b2 COVID-19 vaccines. Immunogenicity was assessed through SARS-CoV-2 antibody titers and neutralizing antibodies (NAbs) at 28 days post-booster, while safety was monitored via adverse event reporting. Results: The results showed that both vaccines demonstrated increased geometric mean titers (GMTs) post-booster. In the ChAdOx1-S booster group, at the baseline visit (day 0) and third visit (day 28), no statistically significant differences in GMT between the half- and full-dose groups were observed (p = 0.970 and 0.539, respectively). In the BNT162b2 group, no statistically significant difference was noted at the baseline visit, while the full dose was higher than the half dose at 28 days (Day 28, p = 0.011). Surrogate virus neutralization tests (sVNTs) and NAbs assays also revealed no significant differences between the half and full dose groups for both the Wuhan strain and the Delta variant. The BNT162b2 group compared to the ChAdOx1-S group revealed a statistically significant increase in IgG levels compared to ChAdOx1-S, with p-values of <0.001 and <0.001 for the half dose and full dose, respectively. This was also reflected in the NAbs test results, where BNT162b2 showed significantly higher levels against both the Wuhan strain and Delta variant. Adverse events were predominantly mild: 79.6% (n = 86/108) in the ChAdOx1-S full-dose group, 75.4% (n = 43/57) in the ChAdOx1-S half-dose group, 84.2% (n = 101/120) in the BNT162b2 full-dose group, and 92.6% (n = 88/95) in the BNT162b2 half-dose group, with pain at the injection site being the most common local reaction and myalgia and headache the most frequent systemic reactions. One serious adverse event was reported, assessed as unrelated to the vaccine. Conclusions: This study confirms that half doses of ChAdOx1-S and BNT162b2 are as immunogenic and safe as full doses, and a heterologous booster is more immunogenic than a homologous booster. Full article

Background/Objectives: Vaccine usage rates (VURs) for COVID-19 vaccines (C19V) in KwaZulu-Natal (KZN), South Africa, remain insufficiently documented. This study assessed VUR for Pfizer–BioNTech (Pfizer) and Janssen Biotech Inc. (J&J) and reviewed monitoring systems in public (PUBS) and private (PRIVS) sectors. Methods: A dual-phase, multicentre study was conducted in PUBS and PRIVS facilities. Phase 1 comprised a retrospective, cross-sectional analysis of VUR for Pfizer and J&J (May 2021–July 2022). Phase 2 involved qualitative interviews with public (PUBSR) and private (PRIVSR) sector respondents (January–March 2024). Results: Pfizer VURs were 78.7% (PUBS) and 104.4% (PRIVS), while J&J recorded 64.7% (PUBS) and 40.2% (PRIVS). Stock reconciliations were complete across PUBSR and PRIVSR, but challenges persisted in stock on hand, reporting systems, and operational indicators. Conclusions: Pfizer achieved higher VURs than J&J, with PRIVS exceeding 100% due to under-reporting of issued doses. Integrated, real-time monitoring of VURs is urgently required to strengthen evidence-based policymaking, optimise supply chain management, reduce wastage, and improve vaccine uptake. Standardised monitoring frameworks across PUBS and PRIVS are essential to align with national objectives. Full article

A reassessment of the risk-benefit balance of the two lipid nanoparticle (LNP)-based vaccines, Pfizer’s Comirnaty and Moderna’s Spikevax, is currently underway. While the FDA has approved updated products, their administration is recommended only for individuals aged 65 years or older and for those aged 6 months or older who have at least one underlying medical condition associated with an increased risk of severe COVID-19. Among other factors, this change in guidelines reflect an expanded spectrum and increased incidence of adverse events (AEs) and complications relative to other vaccines. Although severe AEs are relatively rare (occurring in <0.5%) in vaccinated individuals, the sheer scale of global vaccination has resulted in millions of vaccine injuries, rendering post-vaccination syndrome (PVS) both clinically significant and scientifically intriguing. Nevertheless, the cellular and molecular mechanisms of these AEs are poorly understood. To better understand the phenomenon and to identify research needs, this review aims to highlight some theoretically plausible connections between the manifestations of PVS and some unique structural properties of mRNA-LNPs. The latter include (i) ribosomal synthesis of the antigenic spike protein (SP) without natural control over mRNA translation, diversifying antigen processing and presentation; (ii) stabilization of the mRNA by multiple chemical modification, abnormally increasing translation efficiency and frameshift mutation risk; (iii) encoding for SP, a protein with multiple toxic effects; (iv) promotion of innate immune activation and mRNA transfection in off-target tissues by the LNP, leading to systemic inflammation with autoimmune phenomena; (v) short post-reconstitution stability of vaccine nanoparticles contributing to whole-body distribution and mRNA transfection; (vi) immune reactivity and immunogenicity of PEG on the LNP surface increasing the risk of complement activation with LNP disintegration and anaphylaxis; (vii) GC enrichment and double proline modifications stabilize SP mRNA and prefusion SP, respectively; and (viii) contaminations with plasmid DNA and other organic and inorganic elements entailing toxicity with cancer risk. The collateral immune anomalies considered are innate immune activation, T-cell- and antibody-mediated cytotoxicities, dissemination of pseudo virus-like hybrid exosomes, somatic hypermutation, insertion mutagenesis, frameshift mutation, and reverse transcription. Lessons from mRNA-LNP vaccine-associated AEs may guide strategies for the prediction, prevention, and treatment of AEs, while informing the design of safer next-generation mRNA vaccines and therapeutics. Full article

Background: In the Kingdom of Saudi Arabia, various COVID-19 vaccines were administered during the pandemic. However, region-specific real-word comparative data on their immunogenicity remain limited. This study aimed to assess the serological responses to Pfizer-BioNTech (BNT162b2), Moderna (mRNA-1273), and AstraZeneca (ChAdOx1 nCoV-19) vaccines in a diverse population living in KSA. Methods: This observational study included 236 adults recruited from vaccination sites in Riyadh. Participants provided serum samples at predefined intervals: before the first dose, after the first dose, after the second dose, and post-vaccination infection (if applicable). IgG and neutralising antibodies were quantified using ELISA assays. Demographic and vaccination data, and their associations with antibody responses, were evaluated. Results: At baseline, 75.4% of participants were positive for SARS-CoV-2 IgG, suggesting high prior exposure. Marked incremental increases in IgG levels were observed after each vaccine dose. Both Moderna and Pfizer elicited stronger responses, with Pfizer inducing the strongest early response and Moderna achieving the highest overall titres. Among IgG-positive individuals, neutralising antibodies were detected in 98.1%. There were no statistically significant differences by age or gender, although males tended to show higher mean titres. Heterologous vaccine schedules induced comparable or enhanced immunogenicity relative to homologous schedules, supporting their use in flexible immunisation strategies. Conclusions: All COVID-19 vaccines administered in Saudi Arabia elicited robust antibody responses, particularly the mRNA-based vaccines. Our findings support their continued use and justify varied vaccination approaches, including mix-and-match booster strategies, to enhance community immunity. Full article

Background: During the global fight against the COVID-19 pandemic, vaccinations have been widely recognized as the most effective and generally safe method for preventing the spread of COVID-19. However, it has been reported that children may experience post-vaccination serious adverse drug reactions (SADRs). Thus, we aimed to analyze the risk of SADRs to COVID-19 vaccines in the pediatric population. Methods: In this retrospective, cross-sectional study, 5422 cases of SADRs (n = 5018 for Pfizer BioNTech, Comirnaty and n = 494 for Moderna, Spikevax) were analyzed after 37,344,343 doses of COVID-19 vaccines were administered. This study covered the European Economic Area. The analysis period for both vaccinations and SADRs spanned from 7 December 2020 to 5 October 2023. The analysis encompassed 207 types of SADRs grouped into 12 categories. All estimated real-world reporting rates were reported as normalized per million ADR reports and adjusted using real-world trial-based scaling (APMR). Results: The total estimated real-world reporting rates of SADRs were 5792 APMR for Comirnaty and 5671 for Spikevax. The most commonly reported clinical categories of suspected SADRs for both vaccines were neuropsychiatric, cardiovascular and gastroenterological disorders. The most often reported SADRs encompassed headaches, myocarditis, episodes of syncope, dizziness and dyspnea. Conclusions: According to the data from this study, several SADRs were reported in children following COVID-19 vaccination. The estimated real-world reporting rates of SADRs related to COVID-19 vaccines seem to be rare among children. Additionally, the data suggest that Comirnaty (Pfizer-BioNTech) may have a similar risk profile compared to Spikevax (Moderna). Full article

Background: Although the safety of COVID-19 vaccines has been demonstrated in clinical trials, real-world pharmacovigilance remains essential to detect rare or unexpected adverse events following immunization (AEFI). In Mexico, the national AEFI surveillance system is in place, yet there is limited analysis of state-level data. Objective: To characterize AEFI related to five COVID-19 vaccines and identify factors associated with AEFI type and seriousness in Nuevo León, Mexico. Methods: A retrospective analysis of the State of Nuevo León AEFI database was conducted, including all AEFI reports between December 2020 and June 2022 (n = 2213). Data included patient sex, age, vaccine type (Pfizer/BioNTech, AstraZeneca, Sinovac, Moderna, CanSino), number of doses (1 or ≥2), symptom categories, and AEFI seriousness. Symptoms were classified as local or systemic and grouped by organ systems. Descriptive analysis and binary multivariate logistic regression were used to examine associations between demographic and vaccine-related factors with AEFI type and severity. Odds ratios (OR) with 95% confidence intervals (CI) were estimated. Results: Most AEFI reports involved females aged 19–59 years and occurred after the first vaccine dose. The most frequently reported unexpected adverse events (UAEs) were mild to moderate, including injection-site reactions, headache, chills, fatigue, nausea, fever, dizziness, weakness, myalgia, and tachycardia. The Pfizer/BioNTech vaccine was associated with higher odds of arm pain and lower odds of hemorrhagic events. Receiving ≥2 doses increased the odds of arm pain and systemic symptoms. Less than 3% of AEFIs were classified as serious. Older adults (≥65 years) and second vaccine doses were associated with increased odds of a serious AEFI, while female sex and receiving the Pfizer/BioNTech vaccine were associated with reduced odds. Conclusions: In Nuevo León, most AEFIs related to COVID-19 vaccination were mild to moderate and resolved without complications. Serious AEFIs were uncommon, with older age and second doses associated with higher risk, and female sex and Pfizer/BioNTech vaccination associated with lower risk. These findings provide a local perspective on vaccine safety that complements national and international evidence. Full article

Background/Objectives: The COVID-19 pandemic was characterized by the rapid transmission of the virus and a global race for vaccines, with vaccines such as AstraZeneca, CoronaVac, Pfizer, and Janssen arriving in Brazil in 2020. Concurrently, an infodemic of information, driven by the media and social media, highlighted the importance of health communication. This study examines how online newspapers in a Brazilian state disseminated information about vaccination and its relationship with vaccine adherence among the population. Methods: Quantitative research, in which a total of 5308 journalistic articles were verified, using two databases, one for the publication of journalistic articles and the other for vaccinations in the state, which applied 9,577,567 doses in the period. Results: The analyses demonstrated a positive correlation between the number of publications of articles and the number of applications of vaccines (rho = 0.407, p-value < 0.0005), revealing a relationship of both increase and decrease in the publication of newspaper articles and the application of vaccines in specific weeks during the analysis period. Vaccination data revealed low adherence to the booster dose by the population, with unequal values among the cities of the state. Conclusions: The study highlighted the potential importance of newspapers in disseminating information about vaccines during the pandemic, underscoring the need for regional health strategies to increase vaccination coverage. Full article

The problem of geolocating Reddit users without access to the author information API is tackled in this study. Using subreddit data, we analyzed and identified user location based on their interactions within location-specific subreddits. Using unsupervised learning methods such as Latent Dirichlet Allocation (LDA) and Non-Negative Matrix Factorization (NMF) algorithms, we examined conversations about COVID-19 and immunization across the U.S., focusing on COVID-19 vaccination. Our topic modeling identifies four themes: humor and sarcasm (e.g., jokes about microchips), conspiracy theories (e.g., tracking devices and microchips in the COVID-19 vaccine), public skepticism (e.g., debates over vaccine safety and freedom), and vaccine brand concerns (e.g., Pfizer, Moderna, and booster shots). Our geolocation analysis shows that regions with lower vaccination rates often exhibit a higher prevalence of misinformation-labeled comments. For example, counties such as Ada County (Idaho), Newton County (Missouri), and Flathead County (Montana) showed both a low vaccine uptake and a high rate of false information. This study provides useful information on the many different examples of misinformation that are disseminated online. It gives us a better understanding of how people in different parts of the U.S. think about getting a COVID-19 vaccine. Full article

We aimed to explore SARS-CoV-2 evolution during in vitro neutralisation using next generation sequencing, and to determine whether sera from individuals immunised with two doses of the Pfizer-BioNTech vaccine (BNT162b2) were as effective at neutralising the variant of concern (VOC) Delta (B.1.617.2) compared to the earlier lineages Beta (B.1.351) and wild-type (A.2.2) virus. Using a live-virus SARS-CoV-2 neutralisation assay in Vero E6 cells, we determined neutralising antibody titres (nAbT) against three SARS-CoV-2 strains (wild type, Beta, and Delta) in 14 participants (vaccine-naïve (n = 2) and post-second dose of BNT162b2 vaccination (n = 12)), median age 45 years [IQR 29–65]; the median time after the second dose was 21 days [IQR 19–28]. The determination of nAbT was based on cytopathic effect (CPE) and in-house quantitative reverse transcriptase real-time quantitative polymerase chain reaction (RT-qPCR) to confirm SARS-CoV-2 replication. A total of 110 representative samples including inoculum, neutralisation breakpoints at 72 h, and negative and positive controls underwent genome sequencing. By integrating live-virus neutralisation assays with deep sequencing, we characterised both functional antibody responses and accompanying viral genetic changes. There was a reduction in nAbT observed against the Delta and Beta VOC compared with wild type, 4.4-fold (p ≤ 0.0006) and 2.3-fold (p = 0.0140), respectively. Neutralising antibodies were not detected in one vaccinated immunosuppressed participant and the vaccine-naïve participants (n = 2). The highest nAbT against the SARS-CoV-2 variants investigated was obtained from a participant who was vaccinated following SARS-CoV-2 infection 12 months prior. Limited consensus level mutations occurred in the various SARS-CoV-2 lineage genomes during in vitro neutralisation; however, consistent minority allele frequency variants (MFV) were detected in the SARS-CoV-2 polypeptide, spike (S), and membrane protein. Findings from countries with high COVID-19 incidence may not be applicable to low-incidence settings such as Australia; as seen in our cohort, nAbT may be significantly higher in vaccine recipients previously infected with SARS-CoV-2. Monitoring viral evolution is critical to evaluate the impact of novel SARS-CoV-2 variants on vaccine effectiveness, as mutational profiles in the sub-consensus genome could indicate increases in transmissibility and virulence or suggest the development of antiviral resistance. Full article

mRNA-LNP-based COVID-19 vaccines, namely Pfizer-BioNTech’s Comirnaty and Moderna’s Spikevax, were successfully deployed to help control the SARS-CoV-2 pandemic, and their updated formulations continue to be recommended, albeit only for high-risk populations. One widely discussed aspect of these vaccines is their uniquely broad spectrum and increased incidence of adverse events (AEs), collectively referred to as post-vaccination syndrome (PVS). Although the reported PVS rate is low, the high number of administered doses among healthy individuals has resulted in a substantial number of reported vaccine-related injuries. A prominent manifestation of PVS is multisystem inflammation, hypothesized to result from the systemic transfection of organ cells with genetic instructions for a toxin, the spike protein, delivered with lipid nanoparticles (LNPs). In this narrative review, we focus on endothelial cells in the microcirculatory networks of various organs as primary sites of transfection with mRNA-LNP and consequent PVS. We outline the anatomical variations in the microcirculation contributing to the individual variability of symptoms and examine the molecular and cellular responses to vaccine nanoparticle exposure at the endothelial cell level with a focus on the pathways of a sustained cascade of toxic and autoimmune processes. A deeper understanding of the mechanisms underlying mRNA-LNP-induced AEs and PVS at the organ and cellular levels is critical for improving the safety of future vaccines and other therapeutic applications of this groundbreaking technology. Full article