Research Appraisals
Evidence-based critical appraisals of the latest medical research, systematically evaluated using Oxford CEBM methodology.
Showing 12 appraisals
BMC health services research
Computational forecasting using Swedish data in the vaccination phase of the COVID-19 pandemic: a systematic literature review deliberating modelling relevance for public health and healthcare.
BACKGROUND: The benefits of computational forecasting in the later phase of the COVID-19 pandemic when vaccines and clinical pharmaceutical interventions were available have seldom been assessed. We aimed to evaluate computational forecasting research applied to Swedish populations in the vaccination phase of the pandemic. METHODS: A systematic search was performed on March 8, 2024 in the electronic databases PubMed, Scopus, Cochrane library, Embase, Love platform and Epistemikos. An updated version of the Risk of bias Opinion Tool (ROBOT) was used to assess the quality of evidence reported in the papers identified in the search. The articles fulfilling the quality criteria were assessed for suitability for meta-analysis. Data were extracted from the selected articles for synthesis of characteristics, and a thematic analysis was used for a qualitative synthesis of the contents. RESULTS: Of 2034 unique publications identified in the database search, 6 articles satisfied the selection and quality criteria. Variability in the reporting of forecasting performance results was found to make a quantitative meta-analysis of forecast performance infeasible. The data synthesis showed that statistical modeling using Bayesian calibration was the most common methodological approach. No external model validation was reported, but 5/6 articles included internal model corroboration data. The primary theme resulting from the qualitative synthesis of article content was design or refinement of computational models with demonstration of model use in health service practice as a secondary theme. None of the articles referred to health service policymaking as the primary research context. CONCLUSION: Computational forecasting research using Swedish population data from the vaccination phase of the COVID-19 pandemic was deployed in a model design context. While methodological knowledge was developed, most of the research was not initiated to solve the public health and healthcare problems at hand. Our results indicate that the alignment between computational forecasting research and policymaking needs in the vaccination phase of pandemics can be enhanced.
13 July 2026
Read appraisal →Transactions of the Royal Society of Tropical Medicine and Hygiene
Atomic clarity: how structural biology is shaping blood-stage malaria vaccines
Developing an effective malaria vaccine is challenging because Plasmodium parasites use complex strategies to invade host cells. The blood stage, where parasites replicate inside red blood cells, causes disease symptoms and relies on large multiprotein surface complexes that are difficult to target. Understanding their structure is essential for rational vaccine design. Cryogenic electron microscopy (cryoEM) enables atomic-level analysis of dynamic and membrane-associated complexes without crystallization, revealing key processes such as protein trafficking, nutrient uptake, and host cell remodeling. Recent advances in artificial intelligence and deep learning have improved cryoEM data analysis and structural modeling. Together with genomic data, this integrated approach is accelerating progress toward broadly protective malaria vaccines.
9 July 2026
Read appraisal →Human vaccines & immunotherapeutics
Safety and immunogenicity of a booster dose of COVAC-2, a Sepivac SWE™ adjuvanted SARS-CoV-2 recombinant protein vaccine in previously vaccinated healthy adults; a randomized controlled multicentre trial.
This Phase 1 clinical trial evaluated the safety and immunogenicity of COVAC-2, a recombinant protein subunit vaccine as a heterologous booster in adults previously immunized with authorized COVID-19 vaccines (NCT05226702). COVAC-2 contains the SARS-CoV-2 S1 spike protein subunit adjuvanted with Sepivac SWE™, an open-access oil-in-water adjuvant. Sixty participants were randomized to receive a single intramuscular dose of COVAC-2 (10 µg or 25 µg) or placebo, with follow-up through Day 180. The vaccine was well tolerated, with most adverse events being mild or moderate; no serious adverse events were attributed to vaccination. Immunogenicity assessments included spike-binding antibody ELISA, pseudovirus neutralization assays (PNA), ELISpot, and flow cytometry. The 25 µg dose elicited the strongest humoral and cellular responses, with peak antibody titers observed 14 d after COVAC-2 vaccination. While titers waned, they were sustained above baseline through Day 180. ELISpot and flow cytometry revealed elevated IFN-γ and IL-2 responses indicating antigen-specific T-cell activation. Minimal IL-4 and IL-13 responses were demonstrated by flow cytometry. These findings support the safety and immunogenicity of COVAC-2 as a heterologous booster, particularly at the 25 µg dose level. The favorable safety profile, induction of immune responses, and thermal stability of the vaccine formulation suggest its potential utility in global vaccination strategies, especially in low- and middle-income countries. COVAC-2 may offer a scalable and accessible platform for enhancing protection against COVID-19.Clinicaltrials.gov: NCT05226702 - Registered 22 Jul 2022.
13 June 2026
Read appraisal →Archives of microbiology
AI-driven big data analysis and predictive modeling of infectious disease immunity: from correlates to causal, multiscale understanding
The ability to reliably predict protective immunity against infectious diseases remains a central challenge in immunology, vaccine development, and public health. Despite major advances in immunological measurement, immunity prediction has historically relied on simplified correlates most notably antibody titers that often fail to generalize across pathogens, populations, and time. The emergence of large-scale, high-dimensional immune datasets spanning multi-omics, longitudinal cohort studies, electronic health records, and pathogen genomics has created new opportunities for artificial intelligence (AI)-driven modeling. However, early applications reveal that predictive accuracy alone is insufficient and is frequently undermined by spurious correlations, limited generalizability, and a lack of biological interpretability. This review synthesizes current advances and limitations in AI-based immunity prediction, arguing that meaningful progress requires embedding machine learning within immune biology, causal reasoning, and rigorous validation frameworks. We examine the biological foundations of immunity relevant to modeling including innate immune programming, trained immunity, adaptive immune dynamics, and immune memory and map these processes to appropriate data modalities and model classes. We critically evaluate predictive tasks across individual and population scales, from early infection outcomes and vaccine responsiveness to immunity waning and herd-level protection. Emphasis is placed on validation beyond internal cross-validation, on interpretability grounded in immune mechanisms, and on robustness under demographic diversity and pathogen evolution. We conclude that immunity is best understood and predicted as a dynamic, probabilistic, and multiscale system rather than as a static trait. AI has substantial potential to improve infectious disease preparedness and clinical decision-making.
1 June 2026
Read appraisal →Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
Safety and Immunogenicity of a Fourth Dose of Omicron BA.1-Adapted BNT162b2 COVID-19 Vaccines in Adults 18-55 Years Old
BACKGROUND: Emergence of severe acute respiratory syndrome coronavirus 2 sublineages warrants the use of sequence-adapted vaccines to provide protection against coronavirus disease 2019. METHODS: In this phase 3 trial, adults 18‒55 years old who had previously received three 30 μg doses of BNT162b2 vaccine were randomized to receive a 60 or 30 μg dose of bivalent Omicron BA.1‒adapted BNT162b2 comprising equal amounts of ancestral and monovalent messenger RNA BA.1 (bivalent BA.1) or a 60 μg dose of monovalent Omicron BA.1‒adapted BNT162b2 (monovalent BA.1). Safety (local reactions, systemic events, adverse events [AEs], and serious AEs) was the primary objective. Exploratory analyses assessed immune responses against Omicron BA.1, BA.4, and BA.5 subvariants and ancestral strain. RESULTS: Among the 1054 randomized participants who received monovalent BA.1 or bivalent BA.1, frequencies of local reactions, systemic events, and AEs were slightly higher with 60 µg monovalent BA.1 than either bivalent BA.1 dose level. One month after vaccination, bivalent BA.1 (30 and 60 μg) and monovalent BA.1 (60 μg) induced substantial neutralizing responses against Omicron BA.1 (50% neutralizing titer geometric mean fold rises [GMFRs], 15.4 [95% CI 12.4-19.2], 17.1 [13.7-21.4], and 24.6 [19.3-31.4], respectively) and ancestral strain (GMFRs, 6.2 [5.1-7.6], 7.3 [6.0-8.9], and 7.0 [5.7-8.7], respectively). In a smaller (n = 30/treatment arm) sentinel cohort, all study vaccines modestly neutralized Omicron BA.4 and BA.5. CONCLUSIONS: Bivalent and monovalent BA.1‒adapted vaccines had a safety profile similar to the original BNT162b2 30 μg and induced substantial neutralizing responses against Omicron BA.1 and ancestral strains. CLINICAL TRIALS REGISTRATION: NCT04955626.
22 May 2026
Read appraisal →Expert review of vaccines
Approaches to observational study designs and analytical options to evaluate the safety of multi-dose vaccines: a systematic review
INTRODUCTION: Observational studies require careful considerations when evaluating the safety of multidose vaccines. We reviewed design and analytical approaches in observational studies evaluating the safety of multidose vaccines in the post-licensure phase. METHODS: EMBASE, MEDLINE, Web of Science, and Scopus (2018-2022) were searched for hypothesis-testing studies evaluating the safety of multidose vaccines. Key features from frequently used designs were extracted. RESULTS: Among 123 eligible studies, cohort (46%) and self-controlled case series (SCCS)/self-controlled risk interval (SCRI) (40%) followed by case-control (12%) were the most common designs, and 15% of studies used multiple designs. Among cohort studies evaluating multiple doses, vaccination date (36%) and cohort entry with time-updated exposure status (32%) were frequent approaches used to define time zero. Twenty-eight percent of cohort studies did not report time zero; all but one evaluated COVID-19 vaccine effect on post-delivery and fertility-related outcomes. For SCCS/SCRI, 64% of studies accounted for event-dependent exposures, mainly by including pre-exposure periods (53%) and modified SCCS model (48%), while 20% employed multiple correction strategies. Among studies using multiple designs, 68% reached consistent conclusions. CONCLUSIONS: SCCS/SCRI and cohort designs dominate multidose vaccine safety studies. Clear reporting on time zero in pregnancy and fertility-related cohort studies, and on addressing event-dependent exposures in SCCS/SCRI studies is needed, along with guidance on interpreting results from multiple designs. Observational studies are important for assessing safety of vaccines especially for rare health outcomes that cannot be easily detected in randomized trials. Commonly used approaches include comparing these health outcomes between vaccinated and unvaccinated individuals or between different time points in relation to vaccination timing within individuals. However, both approaches have important design challenges. For example, comparison between vaccinated and unvaccinated individuals requires careful consideration of alignment of the time of starting to observe outcomes with the time when individuals become eligible and vaccination time for both comparison groups (time zero). Within-individual comparison requires that earlier occurrence of health outcomes does not influence whether someone receives later vaccine dose(s). These challenges become more complex to address when vaccines are given in multiple doses.In this review, we assessed how important design and analytical issues are handled and reported in published studies evaluating the safety of multidose vaccines and assessed agreement between different study designs when more than one is used.We found that 28% of studies comparing vaccinated and unvaccinated groups did not clearly report time alignment (time zero) mostly with studies on pregnancy and fertility outcomes. Similarly, about one-third of studies using within-individual comparison did not report checking and addressing the possibility that earlier outcomes could influence future vaccinations. When multiple designs were used, two-thirds of studies reached similar conclusions, although comparisons were mainly qualitative. Future work is needed to guide clear reporting of these issues to improve transparency in design and analysis and when comparing results across different designs.
19 May 2026
Read appraisal →Vaccine
Effect of time-of-day vaccination on the antibody response to mRNA and protein COVID-19 vaccine in adults
Time-of-day vaccination has been suggested as a feasible method to boost COVID-19 vaccine immunogenicity particularly in high-risk groups. However, several studies report inconsistent findings. We explored if time-of-day vaccination influences antibody responses to a fourth dose of mRNA (Moderna bivalent vaccine; mRNA-1273.214/mRNA-1273.222) or protein (Novavax; NVX-CoV-2373) COVID-19 vaccine as part of a randomised controlled trial (RCT) in Melbourne, Australia. Furthermore, we assessed if time-of-day vaccination effects differed by vaccine type or sex. At day 28 post-vaccination, antibody responses to all SARS-CoV-2 variants tested were higher for morning compared to afternoon vaccination in the Moderna group. Males in the Moderna group responded with higher antibodies to all SARS-CoV-2 variants tested after morning vaccination while responses in females were unaffected by time-of-day vaccination. Time-of-day vaccination had no effect on the response to Novavax, regardless of sex. Larger randomised trials are needed to confirm these findings to optimise vaccine timing strategies.
13 May 2026
Read appraisal →Vaccine
Effects of candidate vaccines against Zika virus infection: A systematic review of the clinical trials
INTRODUCTION: The 2015-2016 Zika virus (ZIKV) pandemic revealed a pathogenic potential, including Guillain-Barré syndrome and Congenital Zika Syndrome (CZS). Despite the decline in incidence, the potential for future circulation and the absence of specific antivirals underscore continued scientific interest in prophylactic vaccine development. OBJECTIVE: To synthesize evidence from clinical trials regarding the safety and preliminary immunogenicity of current ZIKV vaccine candidates. METHODS: This systematic review followed PRISMA guidelines (CRD420251056463). Searches were performed in MEDLINE, Embase, Web of Science, SciELO, and LILACS for clinical trials published between 2015 and 2025. Risk of bias was assessed using the Cochrane RoB 2 tool. RESULTS: Ten Phase 1 clinical trials were included, evaluating four platforms: inactivated virus (ZPIV, TAK-426, VLA1601), DNA (GLS-5700, VRC5283), mRNA (mRNA-1325, mRNA-1893), and viral vector (Ad26.ZIKV.001). All candidates demonstrated acceptable safety profiles, with predominantly mild-to-moderate and transient adverse events (e.g., injection site pain, fatigue, and headache); no vaccine-related serious adverse events were reported. Most platforms induced robust neutralizing antibody responses. Specifically, TAK-426 showed immune persistence for up to two years, while mRNA-1893 maintained responses for 13 months. The viral vector vaccine (Ad26.ZIKV.001) achieved 100% seroconversion with a single dose. Previous orthoflavivirus exposure did not significantly hinder vaccine-induced immunogenicity. Most studies presented a low risk of bias. CONCLUSIONS: ZIKV vaccine candidates across diverse technological platforms are safe and highly immunogenic. The evidence of long-term durability and the success of single-dose or mRNA regimens support the progression of the most promising candidates to Phase 2/3 trials.
12 May 2026
Read appraisal →Molecular pharmaceutics
mRNASyner: An Integrative Framework for Full-Length mRNA Sequence Optimization via Multimodule Synergistic Design
Messenger RNA (mRNA) technology holds great promise in biomedicine; however, its therapeutic efficacy relies heavily on translation efficiency and the in vivo stability of mRNA sequences, both of which are governed by dynamic interactions between the coding and noncoding regions. Existing optimization approaches typically focus on individual sequence components and lack the capacity for global, synergistic optimization. Moreover, their performance is often limited when processing long sequences or supporting iterative sequence refinement. To overcome these challenges, we propose a unified and interpretable in silico framework for full-length mRNA sequence design, integrating CDS optimization, UTR generation, and degradation modeling. In silico case studies based on respiratory syncytial virus (RSV) vaccine design demonstrated that mRNASyner achieved a favorable balance between translational accessibility and structural stability. mRNASyner thus enables the design of full-length mRNA sequences, supports long-sequence optimization, and offers a novel solution for the development of personalized mRNA therapeutics.
11 May 2026
Read appraisal →Human vaccines & immunotherapeutics
Incidence of Bacille Calmette-Guérin associated lymphadenitis in healthy children: A systematic review and meta-analysis
Few systematic reviews or meta-analyses have addressed on the incidence of Bacille Calmette-Guérin (BCG) lymphadenitis in healthy children. A systematic literature search was independently conducted by two researchers using four English and Korean databases (PubMed, Scopus, KMbase, RISS). The risk of bias was assessed. A total of 52 peer-reviewed journal articles (about 1.8 million children) were included in meta-analyses. The incidence proportion of BCG lymphadenitis ranged from 0.0% to 25.6%. The pooled incidence proportion was 2.5% (95% CI, 1.6-3.6; I2 = 99%). Studies employing active (vs. passive) surveillance reported a significantly higher incidence proportion of lymphadenitis, as did randomized controlled trials (vs. prospective and retrospective cohort studies). Also, the incidence significantly differed according to study quality, publication period, and BCG strain. This study highlights substantial variability in the incidence of BCG lymphadenitis among diverse studies and underscores the influence of surveillance methods, study design, and vaccine strain on reported outcomes.
10 May 2026
Read appraisal →Vaccine
Adenovirus type 5 vector-based COVID-19 vaccine does not increase the likelihood of HIV infection
BACKGROUND: There is a concern about the potential increased risk of acquiring HIV infection after vaccination with adenovirus type 5 (Ad5) vector-based vaccines. We aimed to investigate whether Ad5-nCoV increases the risk of HIV infection. METHODS: Between September 2020 and March 2021, a Phase 3 clinical trial was executed to evaluate the efficacy of Ad5-nCoV. This trial, employing a double-blind, randomized, and placebo-controlled design, enrolled 44,247 participants from 66 clinical sites spanning Argentina, Chile, Mexico, Russia, and Pakistan. Participants were allocated randomly in a 1:1 ratio to receive either Ad5-nCoV or a placebo, and their HIV-negative status was assessed by self-report and confirmed by HIV testing on a baseline blood sample at the end of the study. Consequently, individuals initially administered a placebo received one dose of Ad5-nCoV, while those initially given Ad5-nCoV finally received two doses, with an interval of approximately 6-10 months between administrations. The trial design and primary outcomes have been previously reported. This analysis involves a comprehensive assessment of the associations between pre-existing Ad5 neutralizing antibodies, HIV prevalence and incidence before and after vaccination while accounting for demographic variables. RESULTS: A total of 43,780 participants who had valid HIV baseline testing results were included in this study. Prior to vaccination, there was no discernible difference in HIV prevalence between the placebo group (0·39% of 21,877 participants) and the Ad5-nCoV group (0·38% of 21,893 participants). This similarity persisted when the data were stratified by country, gender, age, and race. Paired analyses assessing HIV incidence were conducted on participants who tested negative for HIV before vaccination, with data collected over a 6-month period post-vaccination. The results revealed notable similarity in HIV incidence across all groups: 0·29% for Group A (Ad5-nCoV group), 0·21% for Group B (Placebo group), 0·27% for group A + D (Ad5-nCoV group and 1 × Placebo+1 × Ad5-nCoV group), 0·1% for Group C (2 × Ad5-nCoV group), and 0·25% for Group A + C + D (participants who received at least one dose of Ad5-nCoV). Testing approximately 100 randomly chosen participants in each country revealed a similar distribution of pre-existing Ad5 neutralizing antibodies (Nab), with the ratio above a titer of 200 ranged from 65·42% to 67·71%. Notably, the heightened presence of pre-existing Ad5 Nab did not result in an increased risk of HIV infection. CONCLUSION: The Ad5-nCoV did not increase the short-term risk of HIV infection in this large and diverse sample of the general population, regardless of the presence of pre-existing Ad5 Nab providing valuable insights into the safety of Ad5 vector-based vaccines. CLINICALTRIALS: gov, NCT04526990.
12 Apr 2026
Read appraisal →N Engl J Med
Adenoviral Inciting Antigen and Somatic Hypermutation in VITT
BACKGROUND: Vaccine-induced immune thrombocytopenia and thrombosis (VITT) is a rare prothrombotic complication that occurs after adenoviral vector-based vaccination against coronavirus disease 2019; in rare cases, it can also occur after natural adenovirus infection. VITT is mediated by platelet-activating antibodies against the highly cationic protein platelet factor 4 (PF4). The underlying inciting antigen trigger and immunopathogenesis remain unknown. METHODS: We used antibody proteomics to determine the amino acid sequences of anti-PF4 antibodies from 21 patients with VITT and sequenced the genes encoding the immunoglobulin light-chain hypervariable region from 100 patients with VITT. To identify an adenoviral trigger, we used the antigen-binding fingerprints of anti-PF4 and anti-adenovirus protein antibodies to identify a shared serum clonotype and subsequently used adenovirus protein peptides and recombinant anti-PF4 VITT antibodies to map the mimicking linear epitope. RESULTS: Genomic and proteomic profiling of VITT antibodies revealed a shared immunoglobulin light-chain allele, IGLV3-21*02 or *03, harboring a critical somatic hypermutation, K31E. Only antibodies purified against adenoviral core protein VII (pVII) contained anti-PF4 species matching the VITT fingerprint; antibodies against intact virions or other adenoviral proteins did not. Cross-reactive IgGs were mapped to a basic linear epitope on pVII. A pathogenic anti-PF4 VITT antibody, back-mutated to germline (K31), lost its prothrombotic activity in vitro and in vivo and preferentially bound pVII, a finding that directly supported the role of the hypermutation in the antigenic shift from adenovirus pVII to PF4. CONCLUSIONS: The results of our study indicate that VITT occurs when, in persons with immunoglobulin light-chain allele IGLV3-21*02 or *03, a specific somatic hypermutation develops that affects antibodies that recognize a specific epitope on the adenoviral core protein pVII, which results in misdirection of antibody targeting toward PF4. (Funded by Deutsche Forschungsgemeinschaft and others; German Clinical Trials Register number, DRKS00025738; EU Post-Authorization Study Register number, EUPAS45098.).
1 Feb 2026
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