Search Results (899)

Background: COVID-19 vaccination has demonstrated a favorable safety profile in children; however, factors associated with the occurrence of adverse events (AEs) following immunization remain insufficiently characterized. This study aimed to identify the demographic and clinical factors associated with AEs following COVID-19 vaccination in children aged 5–11 years. Methods: We conducted an ambispective observational cohort study in Madrid, Spain, including children aged 5–11 years vaccinated with the 10 µg formulation of BNT162b2 (Comirnaty^®, Pfizer-BioNTech). Data were obtained from vaccination registries, electronic health records, and structured telephone interviews with parents or legal guardians. Demographic characteristics, anthropometric variables, previous SARS-CoV-2 infection, medical history, and concomitant medication use were evaluated. Univariable analyses and multivariable logistic regression were performed to identify factors independently associated with the occurrence of suspected AEs. Results: A total of 2026 children were included. Suspected AEs were reported in 759 participants (37.5%). In univariable analyses, greater weight, height, pre-existing medical conditions, concomitant medication use, clinically vulnerable status, and previous SARS-CoV-2 infection were significantly associated with AEs. In the multivariable model, previous SARS-CoV-2 infection (OR 4.07, 95% CI 3.13–5.30), number of concomitant medications (OR 7.77, 95% CI 5.22–11.56), number of pre-existing medical conditions (OR 1.86, 95% CI 1.62–2.14), and height (OR 1.03, 95% CI 1.01–1.04) remained independently associated with AEs. Age, sex, body mass index, and clinically vulnerable status were not independently associated with AE occurrence. Conclusions: In this large real-world pediatric cohort, previous SARS-CoV-2 infection, comorbidity burden, and concomitant medication use were independently associated with adverse events following COVID-19 vaccination. These findings suggest that underlying clinical complexity may be a more important determinant of post-vaccination reactogenicity than demographic characteristics and support the value of individualized pre-vaccination assessment in pediatric populations. Full article

Background/Objectives: Respiratory syncytial virus (RSV) causes morbidity in older adults with cardiovascular disease, in whom infection may precipitate severe lower respiratory tract disease, hospitalization, functional decline, and cardiovascular destabilization. We evaluate the evidence for RSV vaccination in cardiovascular disease and propose a jurisdiction-adaptable framework for integrating vaccination into cardiovascular care. Methods: Observational studies, randomized trials, pragmatic and test-negative studies, prespecified cardiovascular analyses of DAN-RSV, and eligibility recommendations were narratively synthesized and translated into a pathway encompassing patient identification, eligibility and risk assessment, vaccine delivery and co-administration, documentation, and follow-up. Results: Acute cardiac events are frequent during RSV hospitalization, and cardiovascular risk may persist after infection. Randomized trials establish protection against RSV-associated lower respiratory tract disease and respiratory illness, while real-world studies support effectiveness against RSV-related hospitalization. DAN-RSV reduced all-cause cardiorespiratory hospitalization but did not demonstrate significant reductions in cardiovascular hospitalization, myocardial infarction, heart failure (HF) hospitalization, atrial fibrillation, stroke, cardiovascular death, or major adverse cardiovascular events; observational associations with lower post-vaccination cardiovascular-event rates remain hypothesis-generating. The framework prioritizes adults aged ≥75 years and those aged 50–74 years with high-risk cardiovascular conditions where consistent with national recommendations, embeds vaccination assessment across cardiology, HF, primary care, pharmacy, and long-term care, and incorporates co-administration, documentation, and outcome surveillance. Conclusions: The principal contribution is a pathway for moving RSV vaccination from recommendation to routine preventive care for adults with cardiovascular disease. It anchors implementation in established RSV and cardiorespiratory benefits while treating cardiovascular-event reduction as a research priority rather than a demonstrated indication. Full article

Background: Persistent human papillomavirus (HPV) can cause low- or high-grade cervical lesions, which may progress to cervical cancer. This prospective, multicenter, real-world study assessed the effectiveness, tolerability and safety of a Coriolus versicolor-based vaginal gel for the regression of HPV-related low-grade cervical lesions in routine Greek practice. Methods: PAPILOBS-GR is a multicenter, open-label, non-interventional, prospective observational, non-comparative study conducted across 45 sites in Greece. Women aged ≥18 years with ASCUS/LSIL cytology and concordant colposcopy were enrolled. Participants received Coriolus versicolor-based vaginal gel for six months. A second 6-month cycle was offered if needed. The primary endpoint was lesion regression. Secondary endpoints included HPV clearance, patient satisfaction, biopsy evolution, tolerability, and safety. Results: Of 524 enrolled patients (mean age: 34.4 ± 10.0 years; 40.5% HR-HPV), 494 (94.3%) completed the study. Overall, 75.9% achieved lesion regression (72.1% at 6 months and 34.0% at 12 months). HPV clearance occurred in 72.0% overall (68.1% at 6 months and 50.0% at 12 months). Exploratory comparisons showed generally consistent effectiveness across subgroups, including women with HR-HPV, those aged >40 years, and vaccinated participants. No significant differences in clinical endpoints were observed in association with age or vaccination status. Among 22 patients with baseline and 12-month biopsies, 59.1% showed histological improvement. Satisfaction scores exceeded 8/10 at 6- and 12-month follow-ups. Only two non-serious possibly product-related adverse events were reported. Conclusions: Coriolus versicolor-based vaginal gel was associated with high rates of lesion regression and excellent tolerability, reinforcing previous clinical findings and supporting its potential role as an adjunctive approach during watchful waiting for HPV-positive low-grade cervical lesions. Full article

Background: Cervical cancer remains a major public health problem, causing approximately 660,000 new cases and 348,000 deaths annually, with more than 90% occurring in low- and middle-income countries. The WHO African Region accounts for approximately 20% of global cases and 30% of deaths. In November 2020, the World Health Assembly adopted the Global Strategy for Cervical Cancer Elimination with 90–70–90 targets for 2030. Multi-age cohort (MAC) campaigns have emerged as a high-impact strategy for achieving population-level HPV vaccination coverage. This study documents the implementation and outcomes of HPV MAC campaigns across Côte d’Ivoire, Ghana, Liberia, and Sierra Leone in 2025. Methods: This multi-country mixed-methods analysis integrated quantitative administrative campaign data with qualitative programmatic assessments across eight operational readiness domains from the WHO Immunization Readiness Assessment Tool. Data were collected between January and December 2025 from national reports, WHO supervision missions, and partner reports. Coverage analysis used administrative data triangulated with independent monitoring. Equity analysis used school enrolment data and geographic accessibility indices. Results: The campaigns targeted 7,376,096 girls aged 9–18 years and reached approximately 6,306,294, achieving 85.5% overall coverage. Côte d’Ivoire, Ghana, Liberia and Sierra Leone reported administrative coverage of 88.0%, 84.5%, 60.0% and 100%, respectively. All four countries achieved the minimum operational readiness threshold of 80% across all assessed domains. A total of 35,860 health workers were trained, with post-training competency scores increasing from 58.8% to 89.5%. Cold chain functionality exceeded 98% across all campaigns. A total of 314 cases of Adverse Events Following Immunization (AEFIs) were reported, all classified as mild, giving an approximate rate of 5.0 per 100,000 doses. Coverage gaps between in-school and out-of-school girls ranged from 18 to 35 percentage points. Conclusions: The findings suggest that large-scale adolescent HPV immunization can be successfully implemented in resource-limited settings when supported by political commitment, multisectoral coordination and adequate operational resources. The single-dose schedule transition under Gavi 6.0 offers opportunities to simplify delivery. Priority actions include integrating HPV into routine immunization, scaling equity strategies for out-of-school girls and ensuring sustainable financing. Full article

Background/Objectives: Autoimmune and immune-mediated adverse events coded in reports listing COVID-19 vaccines as suspect products are rare, heterogeneous, and difficult to evaluate in spontaneous reporting systems. We characterized autoimmune reporting signals using strict case definitions and an active-comparator disproportionality design. Methods: FAERS reports from 2021Q1 to 2023Q4 were deduplicated and harmonized by vaccine product, platform, sex, age group, and MedDRA Preferred Term (PT). COVID-19 vaccine reports recorded as primary or secondary suspect products were compared with traditional non-COVID vaccine reports. Strict autoimmune events were grouped into neurological, endocrine, rheumatological, hematological, dermatological, and cardiac categories. Reporting odds ratios (RORs), proportional reporting ratios (PRRs), PT-level rankings, masking audits, and sensitivity analyses were evaluated. Results: The primary analysis included 4191 COVID-19 vaccine reports, 2817 comparator reports, and 311 strict-autoimmune reports contributing 316 report-category observations. Positive category-level signals were identified for dermatological (ROR 10.49; 95% CI: 2.51–43.86), endocrine (ROR 5.39; 95% CI: 1.24–23.48), hematological (ROR 4.68; 95% CI: 2.32–9.44), and neurological events (ROR 1.63; 95% CI: 1.16–2.29). Rheumatological reporting was lower, strict cardiac events were absent, and hematological signals were most consistent across sensitivity analyses. Among five adjusted-positive finite PT signals, immune thrombocytopenia was more stable, multiple sclerosis intermediate, and acquired hemophilia, myasthenia gravis, and optic neuritis sparse/imprecise. A post hoc audit identified four potential clusters among 20 acquired-hemophilia reports; cluster collapse reduced the ROR to 2.70 (95% CI 0.30–24.18; p = 0.654). Conclusions: These findings are hypothesis-generating and do not establish incidence, absolute risk, or causality. Full article

Background: The interaction between COVID-19 vaccination and immune checkpoint inhibitor (ICI) therapy in advanced non-small cell lung cancer (NSCLC) remains incompletely characterized. Methods: Retrospective cohort study of 139 patients with stage IV NSCLC treated with first-line ICI-based therapy, stratified by vaccination status and total doses received (0–1 vs. ≥2). Progression-free (PFS) and overall survival (OS) were analyzed by Kaplan–Meier and Cox regression; logistic regression explored factors associated with treatment-related toxicity. Results: Vaccinated patients had longer median PFS (13.0 vs. 11.0 months) and OS (29.0 vs. 24.0 months; both p < 0.001). In multivariable models these associations were attenuated and of borderline significance (OS HR = 0.83, 95% CI 0.69–0.99; PFS HR = 0.79, 95% CI 0.62–0.99). Outcomes were also more favorable with ≥2 doses (median PFS 14.0 vs. 12.0 months, p = 0.001; median OS 30.0 vs. 24.0 months, p < 0.001), and tumor mutational status was the strongest independent predictor of survival. In an exploratory model, ≥2 doses were associated with higher odds of any-grade toxicity (OR = 2.47, p = 0.037); events were predominantly low grade, with no Grade 4 or 5 toxicity. Conclusions: COVID-19 vaccination was associated with improved PFS and OS in stage IV NSCLC receiving first-line ICI therapy, with a dose-related pattern. The association was attenuated after adjustment for tumor biology and is hypothesis-generating. These findings support the safety and potential clinical relevance of vaccination in this population and underline the need for structured monitoring during immunotherapy. Prospective validation is required. Full article

Vaccination ranks among the most consequential interventions in medicine, yet cold-chain dependence, sharps hazards, needle phobia, and reliance on trained vaccinators limit coverage where vaccine-preventable mortality is highest. Microneedle patches deposit antigen into the antigen-presenting-cell-rich epidermis and upper dermis through projections that penetrate the stratum corneum without reaching dermal nociceptors. Such targeting yields immunogenicity matching or exceeding intramuscular injection at a fraction of the antigen mass, with dose-sparing up to six-fold recorded for influenza, polio, and SARS-CoV-2 antigens. Solid-state formulation converts that immunological advantage into a logistical one, since polymeric matrices preserve potency for as long as two years at ambient temperature, removing the refrigeration infrastructure that consumes significant delivery cost. Six microneedle types have reached preclinical or clinical maturity, with dissolving microneedle patches the most advanced. Two trials provide the clinical evidence: a Phase I influenza study showing non-inferior antibody responses and successful self-application, and a Phase I/II measles–rubella trial in The Gambia reaching 93% measles and 100% rubella seroconversion in infants without related serious adverse events. Engineering advances currently include an automated printer producing thermostable mRNA–lipid nanoparticle patches that retain bioactivity for six months at ambient temperature, the first intradermal self-amplifying RNA patch, and quantum-dot on-body immunization records. Sterility assurance, dose uniformity, nucleic acid integrity within solid matrices, and fragmented regulatory guidance remain the challenging obstacles, alongside a clinical pipeline concentrated on few antigens. This review integrates the mechanistic, materials, manufacturing, clinical, regulatory, and global health dimensions of the field to guide translation and equitable deployment. Full article

Background: Pharmacovigilance systems have flagged possible associations between mRNA COVID-19 vaccination and systemic autoimmune inflammatory rheumatic diseases (AIRDs), generating uncertainty for rheumatologists counselling patients. As the first population-scale deployment of an mRNA vaccine platform, COVID-19 vaccination provides a unique setting to examine whether autoimmune safety signals detected in spontaneous reporting systems correspond to measurable disease risk. We synthesised pharmacovigilance and population-based evidence on incident EULAR-defined systemic AIRDs after mRNA COVID-19 vaccination and assessed whether disproportionality signals were corroborated by analytical studies. Methods: We conducted a PRISMA 2020-compliant systematic review searching MEDLINE, Web of Science, Scopus, Embase, and the Cochrane Library from 2019 to April 2026, supplemented by medRxiv and trial registries. Eligible studies included pharmacovigilance disproportionality analyses and analytical studies, including cohorts and randomised controlled trials, evaluating BNT162b2 or mRNA-1273 in adults without known pre-existing autoimmune disease. Risk of bias was assessed using READUS-PV, ROBINS-I, and RoB 2. Meta-analysis was not performed because of substantial heterogeneity. Results: Fourteen studies were included: seven pharmacovigilance studies and seven analytical studies. Disproportionality analyses suggested increased reporting of selected AIRDs, most consistently polymyalgia rheumatica and giant cell arteritis, mainly when all other adverse-event reports served as comparators. These signals were largely neutral when influenza vaccines were the reference. Across analytical studies, associations were inconsistent; modest increases in systemic lupus erythematosus appeared only in selected analyses. Long-term evidence was scarce: only four studies, from three countries (South Korea, Israel, and Norway), followed participants for up to approximately one year, and three of these reported at least one positive association—systemic lupus erythematosus, post-booster rheumatoid arthritis, and polymyalgia rheumatica in older adults—whereas studies restricted to risk windows of three months or less reported no increase. Conclusions: The available evidence does not indicate a consistent increase in incident systemic AIRDs after mRNA COVID-19 vaccination. Although pharmacovigilance studies identified comparator-dependent signals for selected diseases, particularly polymyalgia rheumatica and giant cell arteritis, these findings were generally not confirmed in comparative population-based studies and should be considered hypothesis-generating. Delayed-onset disease remains poorly characterised, and studies with at least one year of follow-up are needed. Full article

Background and Clinical Significance: The COVID-19 pandemic led to the rapid development of effective vaccination strategies. Although COVID-19 vaccines are generally safe, rare hematological adverse events have been reported, most prominently vaccine-induced immune thrombotic thrombocytopenia (VITT). Isolated cases of autoimmune cytopenias and bone marrow failure syndromes following COVID-19 vaccination have also been described. Case Presentation: We report the case of an 80-year-old male who developed subacute-onset severe normocytic anemia with reticulocytopenia and mild leukopenia following heterologous COVID-19 vaccination with ChAdOx1 nCoV-19 (AstraZeneca) and BNT162b2 (Pfizer–BioNTech). Seven days after the second vaccination, mild anemia was detected, progressing over the following weeks to symptomatic anemia requiring hospitalization. Extensive diagnostic evaluation revealed no evidence of hemolysis, nutritional deficiency, autoimmune disease, or viral infection, including SARS-CoV-2 and Parvovirus B19. Bone marrow examination demonstrated an erythroid maturation arrest at the proerythroblast stage, resembling a pure red cell aplasia (PRCA)-like pattern. Cytogenetic and molecular analyses excluded myelodysplastic syndromes. Treatment with erythropoietin resulted in complete hematologic recovery. Conclusions: This case suggests that, in rare instances, COVID-19 vaccination may be temporally associated with transient suppression of erythropoiesis. Further studies are required to elucidate underlying mechanisms and to guide diagnosis and management. Full article

Vaccine-associated anterior uveitis (VAAU) is an uncommon ocular inflammatory phenotype reported after several vaccine platforms. It describes anterior segment inflammation occurring after vaccination when infectious, autoimmune, idiopathic, medication-related, and other possible causes have been reasonably excluded. The current literature indicates that post-vaccination uveitis is rare relative to the scale of immunization, although anterior uveitis is frequently reported among post-vaccination ocular inflammatory events. Evidence remains limited by reliance on case reports, case series, retrospective cohorts, and passive surveillance data, which restricts precise incidence estimation and causal interpretation. Accordingly, the available evidence primarily supports a temporal association rather than a confirmed causal relationship. Proposed mechanisms include innate immune activation, molecular mimicry, adjuvant- or formulation-related immune stimulation, bystander activation, delayed-type hypersensitivity, and host susceptibility related to prior uveitis, autoimmune disease, immune dysregulation, or genetic predisposition. Clinically, VAAU may present with redness, pain, photophobia, blurred vision, anterior chamber cells and flare, keratic precipitates, posterior synechiae, elevated intraocular pressure, vitritis, or cystoid macular edema. Most cases described in the literature are mild to moderate and improve with topical corticosteroids and cycloplegic therapy, whereas recurrent, severe, or treatment-intensive courses have been reported mainly in predisposed individuals. Future work should emphasize active surveillance, standardized phenotype-specific reporting, harmonized case definitions, and mechanistic studies to better define risk, recurrence patterns, and causality. Careful interpretation of suspected cases can support accurate diagnosis, patient counseling, and vaccine-safety monitoring without undermining clinically indicated immunization. Full article

Aquaculture production of Asian seabass is increasingly threatened by recurrent bacterial diseases, while practical vaccination strategies that provide protection against bacterial challenges involving multiple pathogens during extended grow-out periods remain limited. This study evaluated the immunological and protective effects of a sequential mucosal vaccination strategy in juvenile Asian seabass (Lates calcarifer; 200 fish per treatment, distributed among four replicate tanks of 50 fish) against four major bacterial pathogens: Flavobacterium covae, Vibrio harveyi, Vibrio vulnificus, and Photobacterium damselae. The vaccination regimen consisted of two nanoemulsion-based immersion vaccination events administered 14 days apart, followed by three oral chitosan–alginate hydrogel vaccination courses administered for 7, 5, and 3 consecutive days. Bacterial challenge experiments were conducted at three post-vaccination time points using immersion and intraperitoneal injection models. Growth performance and feed conversion were evaluated using replicate-tank means as the experimental units. Sequential vaccination did not significantly affect final body weight, weight gain, average daily gain, specific growth rate, or feed conversion ratio (p > 0.05). Vaccinated fish showed significantly higher antigen-specific IgM levels in skin mucus, intestinal mucus, and serum across the evaluated challenge conditions. Correspondingly, ighm, ighd, and ight expression was increased in the gills, skin, head kidney, and intestine, indicating enhanced immunoglobulin-associated responses in mucosal and lymphoid tissues. Full-length 16S rRNA gene sequencing showed vaccine-associated changes in gill and intestinal bacterial community composition, including a lower relative representation of several challenge-associated taxa and a higher relative representation of selected commensal-associated taxa. Vaccinated fish showed significantly higher cumulative survival following F. covae immersion, mixed V. harveyi/V. vulnificus/P. damselae immersion, and mixed-pathogen injection challenges (p < 0.05). These findings demonstrate that sequential nanoemulsion immersion priming and oral hydrogel boosting enhanced pathogen-specific humoral responses and increased immunoglobulin-gene expression. The sequential vaccination strategy improved survival following a separate Flavobacterium covae challenge and a combined Vibrio harveyi/Vibrio vulnificus/Photobacterium damselae challenge during the experimental period without adversely affecting growth. This needle-free strategy warrants further evaluation under commercial aquaculture conditions. Full article

Background/Objectives: Vaccine-preventable disease may generate medico-legal disputes not only after an adverse event following immunization, but also when a clinician is alleged to have failed to mention, recommend, revisit, refer for, or document a clinically relevant vaccine. We examine this “unmentioned vaccine” problem while distinguishing existing law (lex lata) from proposed good practice (lex ferenda). Methods: We conducted a documented purposive narrative and comparative medico-legal review. PubMed/MEDLINE, PubMed Central, structured scholarly web searches, publicly accessible legal repositories, and official policy websites were searched from database inception through 21 July 2026 using combinations of vaccination, informed consent/refusal, failure to recommend or vaccinate, referral, documentation, negligence, causation, and LMIC terms. Authorities were selected for doctrinal relevance and jurisdictional contrast, with citation chaining. Results: In the selected jurisdictions, patient-centered disclosure of material risks and reasonable alternatives is recognized in differing forms. Vaccine-specific cases are sparse and fact-sensitive and do not establish a universal duty to recommend, refer, or revisit every vaccine. Provider recommendation influences uptake, but this behavioral evidence does not itself establish legal duty or causation, and direct empirical evidence linking counselling omissions to claims remains limited. We therefore present ADRR—assess, discuss and disclose, recommend or refer, and record and revisit—as proposed practice guidelines developed by the authors and presented in conceptual form, not as a validated legal or clinical standard. Conclusions: ADRR may support proportionate, system-level preparedness, especially in LMICs, but implementation must account for access, supply, workforce, financing, records, and legal context. Stakeholder co-design and empirical validation are required before routine adoption. Full article

Both SARS-CoV-2 infection and COVID-19 vaccination have been associated with renal complications. In the context of SARS-CoV-2 infection, kidney injury is primarily attributed to a complex interplay of systemic immune dysregulation and vascular damage. Severe infection triggers a cytokine-mediated inflammatory response characterized by elevated levels of pro-inflammatory mediators, resulting in systemic hemodynamic instability, increased capillary permeability, and renal hypoperfusion, ultimately leading to acute tubular injury. In addition, virus-induced endothelial activation promotes a prothrombotic state, microvascular injury, and further impairment of renal perfusion. Collectively, these processes converge to produce acute kidney injury (AKI) and, in severe or prolonged cases, may contribute to chronic tubulointerstitial damage and progressive renal dysfunction. In contrast, renal manifestations following COVID-19 vaccination are relatively uncommon and are thought to arise primarily from immune-mediated dysregulation rather than direct cytopathic effects. Reported cases include minimal change disease, IgA nephropathy, focal segmental glomerulosclerosis (FSGS), acute interstitial nephritis and other glomerulopathies, which present as either new-onset disease or relapses. These lesions are thought to result from transient immune activation following vaccination, including T-cell stimulation and altered humoral responses, which may trigger or unmask an underlying susceptibility to renal injury. Careful post-vaccination monitoring in high-risk populations may be warranted, and further molecular and population-level studies are needed to elucidate the underlying mechanisms and refine risk assessment. Full article

Background/Objectives: Waning immunity after primary COVID-19 vaccination supports evaluation of additional doses. HXP-GPOVac is an egg-based, inactivated Newcastle disease virus (NDV)-vectored vaccine expressing a prefusion-stabilized SARS-CoV-2 HexaPro spike antigen. We evaluated the safety, tolerability, and immunogenicity of a single additional 10 µg dose of HXP-GPOVac administered to adults previously primed with two doses of either HXP-GPOVac or BNT162b2. Methods: Study GPO NDV-HXP-S 203 was an open-label phase II extension enrolling adults (18–75 years) who previously completed a two-dose primary series in Study 202 with either HXP-GPOVac or BNT162b2 (Pfizer–BioNTech; Comirnaty). All participants received a single additional 10 µg intramuscular dose of HXP-GPOVac ≥ 6 months after their second primary dose. Solicited local/systemic adverse events (AEs) were recorded for 7 days, unsolicited AEs through Day 28, and serious AEs (SAEs) and adverse events of special interest (AESIs) throughout follow-up. Neutralizing antibody titers (pseudovirus 50% neutralization titer, NT₅₀) and anti-spike IgG (BAU/mL) were assessed pre-dose (Day 1) and post-vaccination through 12 months; a predefined subset underwent IFN-γ and IL-5 ELISpot. SARS-CoV-2 infection during follow-up was assessed using anti-nucleocapsid (anti-N) IgG. Symptomatic COVID-19 was identified through symptom-reported, symptom-triggered RT-PCR testing; sequencing was performed when feasible. Results: All 219 participants received HXP-GPOVac (167 primed with HXP-GPOVac and 52 with BNT162b2). Any solicited local reaction occurred in 22.2% (37/167) of HXP-GPOVac-primed and 26.9% (14/52) of BNT162b2-primed participants; any solicited systemic reaction occurred in 10.8% (18/167) and 13.5% (7/52), respectively. No vaccine-related unsolicited AEs or AESIs were reported. Three deaths occurred during the 12-month follow-up; one (a sudden cardiac death in an HXP-GPOVac-primed participant) was assessed by the safety medical team as possibly related to vaccination, and two were assessed as not related. Neutralizing antibody GMTs increased from 46.33 at baseline to 1569.04 at Day 15 in HXP-GPOVac-primed participants and from 77.25 to 841.34 in BNT162b2-primed participants; corresponding SCRs were 78.8% and 76.9%. Anti-spike IgG GMCs increased from 48.79 to 1480.14 BAU/mL and from 194.48 to 1547.88 BAU/mL, respectively. Responses declined over time but remained above baseline through 12 months. In the cellular immunity subset, post-vaccination IFN-γ responses increased, with comparatively modest IL-5 responses and no pattern suggestive of Th2 predominance. Conclusions: A single additional dose of HXP-GPOVac administered ≥6 months after primary vaccination with HXP-GPOVac or BNT162b2 was generally well tolerated and elicited robust recall humoral responses, with supportive findings of cellular immunity. Trial registration: Thai Clinical Trials Registry, TCTR20230213001. Full article

Background/Objectives: COVID-19 vaccines may be given without requiring a negative test or absence of symptoms; however, this recommendation needs further safety evaluation. This study aimed to compare the adverse events following immunization (AEFI) between PCR-positive (asymptomatic/mildly symptomatic) and PCR-negative individuals at the time of vaccination, with a secondary objective of comparing the two vaccines (TURKOVAC and CoronaVac). Methods: This descriptive study was a secondary analysis of phase III clinical trials. Individuals who were positive for SARS-CoV-2 PCR at the time of vaccination constituted the PCR(+) group and those who tested negative or became positive after the 4th day following vaccination constituted the PCR(−) group. Whether participants had a history of COVID-19 was not considered. Results: Data from 5207 individuals were analyzed. AEFIs were more frequent in the PCR(+) group than PCR(−) group: site pain (24.5% vs. 16.7%, p < 0.001), arm pain (9.5% vs. 7.8%, p = 0.008), headache (14.8% vs. 10.0%, p < 0.001), fatigue (14.5% vs. 8.9%, p < 0.001), myalgia (12.3% vs. 7.5%, p < 0.001), sore throat (11.9% vs. 8.1%, p < 0.001), cough (7.9%; 11.1% vs. 6.9%, p < 0.001). These AEFIs were more frequent in the PCR(+) group with both vaccine groups separately. The distribution of AEFIs over time followed similar patterns in PCR(+) and PCR(−) individuals. Local AEFIs were slightly more common with the TURKOVAC, systemic AEFIs with the CoronaVac. Conclusions: While AEFIs were more common among PCR(+) group, they were mild, tolerable, and easily manageable. Our results support the suggestion that routine PCR testing prior to vaccination may not be warranted solely to mitigate concerns about anticipated adverse events. Full article