Search Results (110)

In Ukraine, SARS-CoV-2 detection and national genomic surveillance have been complicated by full-scale war, limited resources, and varying levels of public health infrastructure impacted across the country. Following the Spring of 2022, only a paucity of data have been reported describing the prevalence and variant dynamics of SARS-CoV-2 in the country. Comparative whole genome analysis has overtaken diagnostics as the new gold standard for detecting and tracing emerging variants while showing utility to rapidly inform diagnostics, vaccine strategies, and health policy. Herein, we provide an updated report characterizing the dynamics and prevalence of SARS-CoV-2 in Ukraine from 1 May 2022 to 31 March 2024. The present study extends previous reports for disease incidence Waves 1–4 in Ukraine with the addition herein of Waves 5, 6, and 7, occurring from August to November 2022 (Wave 5), February to May 2023 (Wave 6), and October 2023 to January 2024 (Wave 7). During the study period, the national Case Fatality Rate (CFR) fluctuated between 0.46% and 1.74%, indicating a consistent yet modest rate when compared to the global average. The epidemiological dynamics of Variants of Concern (VOCs) in Ukraine reflected global patterns over this period, punctuated by the rise of the BA.5 lineage and its subsequent replacement by the Omicron subvariants XBB and JN.1. Our analysis of variant dispersal patterns revealed multiple potential spatiotemporal introductions into Ukraine from Europe, Asia, and North America. Our results highlight the importance of ongoing genomic surveillance to monitor variant dynamics and support global efforts to control and mitigate COVID-19 disease risks as new variants arise. Full article

Background: Starting in early 2022, SARS-CoV-2 Omicron has driven large outbreaks in China, a predominantly infection-naive population with high inactivated vaccine coverage. This unique context provided a substantially less-confounded opportunity to evaluate how vaccination, public health, and social measures influenced severity. Methods: We systematically reviewed 86 studies (224 severity estimates) published from 2022 to 2024, reporting symptom and clinical severity outcomes (fever, cough, and sore throat; symptomatic, severe/critical, and fatal illness) of Omicron infections in China. Using meta-regression, we evaluated the associations of study setting, age group, vaccination status, predominant subvariants, and Oxford COVID-19 Government Response Tracker (OxCGRT) indices, including the Government Response Index (GRI), Containment and Health Index (CHI), and the Stringency Index (SI), with infection outcomes, adjusting for key confounders. Results: We found the primary or booster series of inactivated vaccines conferred strong protection against severe/critical illness (pooled relative risk (RR) 0.17 [95% CI: 0.09–0.33]) but did not reduce symptom frequency (RR 0.99 [95% CI: 0.95–1.02]). Each 10-unit increase in GRI or CHI was associated with 7% (95% CI: 1–12%) and 6% (95% CI: 1–10%) lower odds of symptomatic infection and 3% (95% CI: 1–4%) lower odds of severe/critical illness. Later subvariants (BA.5, BF.7, and XBB) showed 24–38% higher odds of upper respiratory symptoms versus BA.1. Conclusions: The data collection context significantly impacted severity estimates, with higher estimates from emergency hospitals. Overall, inactivated vaccines provided strong protection against severe/critical outcomes while stringent public health measures were associated with lower severity. Our findings underscore the importance of consistent and standardized protocols to produce reliable estimates of SARS-CoV-2 severity in evolving epidemiological contexts. Full article

Background/Objectives: To evaluate how immune responses compare among ethnic groups approximately 2 years after receiving a third dose of COVID-19 vaccine (BNT162b2, mRNA-1273, ChAdOx1or BBIBP-CorV), we tested T cell responses and Spike-specific RBD-antibody titer, and neutralized antibody titer levels utilizing Spectral Flow cytometry, ELISA, and SARS-CoV-2 pseudotyped-based neutralization assays, respectively. Methods: Forty-four individuals from January–December 2023 were identified within the cohort and were classified into different ethnic backgrounds; Black (N = 13), Asian (N = 14), Caucasian (N = 17). We recognize that the “Asian” group includes diverse subpopulations with distinct genetic and environmental backgrounds, which could not be further stratified due to sample-size limitations. Spike-specific AIM+, CD4+, and CD8+ T cell responses were assessed and evaluated against SARS-CoV-2 variants, including the ancestral Wuhan, Delta, and multiple Omicron subvariants (B1.1529, BA2.86, BA.4/5, and XBB.1). Alongside we tested the RBD-IgG and neutralizing antibody titers against the ancestral Wuhan. Spearman’s correlation analysis was utilized to determine corelative relationships among the AIM+ and CD4+ T cell responses, as well as the RBD-IgG and neutralizing antibody titers. Results: Our results show robust and comparable RBD-IgG and neutralizing antibody titers across all groups, with a significant positive correlation between these two measurements. Significant differences were observed in T-cell activation, with Asian participants exhibiting lower frequencies of Spike-specific CD4+ T cells against SARS-CoV-2 Omicron subvariants and higher frequencies of cytokine-producing CD4+ T cells (TNF-α, IFN-γ, and IL-2) as compared to the Caucasian group. Breakthrough infection status was not fully controlled and may influence these findings. Conclusion: Despite a small sample size and potential confounding by natural infections within our long-time-span sampling, our data suggest persistent cellular and humoral immunity 2 years after vaccination across ethnicities, with notable differences in T cell activation and cytokine profile. These preliminary observations highlight the need for larger, more detailed studies that consider intra-ethnic diversity and hybrid immunity to better understand ethnic differences in COVID-19 vaccine responses. Full article

Despite various methods for detecting and treating SARS-CoV-2, affordable and easily applicable solutions are still needed. Aptamers can potentially fill this gap. Here, we establish a workflow to identify aptamers that bind to the spike proteins of SARS-CoV-2, a process applicable to other targets as well. The spike protein is crucial for the virus’s entry into host cells. The aptamer development process for the spike protein’s receptor binding domain (RBD) begins with splitting the SARS-CoV-2’s genome into 40 nucleotide-long sequences, predicting their two-dimensional structure, and sorting based on the free energy. Selected oligomers undergo three-dimensional structure prediction and docking onto the viral spike protein’s RBD. Six RNA oligomers were identified as top candidates based on the RNA docking with the SARS-CoV-2 wild-type (WT) (Wuhan-Hu-1 strain) and Omicron variant BA.1 RBD and molecular dynamics simulations. Three oligomers also demonstrated strong predicted binding affinity with other SARS-CoV-2 variants, including BA.2, XBB.1.5, and EG.5, based on the protein–aptamer docking followed by stability evaluation using the MD simulations. The aptamer with the best fit for the spike protein RBD was later validated using biolayer interferometry. The process has resulted in identifying a single aptamer from a library of 29,000 RNA oligomers, which exhibited affinity in the submicromolar range and the potential to develop into a viral screen or therapeutic. Full article

Background/Objectives: Older adults with frailty are at-risk of worse outcomes following respiratory-viral-infections such as COVID-19. Data on effectiveness of vaccination/boosting in frail older adults during Omicron is lacking. Methods: National healthcare-claims data and COVID-19 registries were utilized to enroll a cohort of older Singaporeans (≥60 years) as of 1 January 2022, divided into low/intermediate/high-risk for frailty; matching weights were utilized to adjust for sociodemographic differences/vaccination uptake at enrolment across frailty categories. Competing-risk-regression (Fine-Gray) taking death as a competing risk, with matching weights applied, was utilized to compare risks of COVID-19-related hospitalizations and severe COVID-19 across frailty levels (low/intermediate/high-risk), with estimates stratified by booster status. Individuals were followed up until study end-date (20 December 2023). Results: 874,160 older adults were included during Omicron-predominant transmission; ~10% had intermediate/high-frailty-risk. Risk of hospitalization/severe COVID-19 was elevated in those with intermediate/high-frailty-risk up to XBB/JN.1 transmission. Boosting was associated with decreased risk of COVID-19-related hospitalization across all frailty categories in infection-naïve individuals. However, in infection-naïve older adults with high-frailty-risk, while receipt of first boosters was associated with lower risk of COVID-19-hospitalization/severe COVID-19, additional booster doses did not reduce risk. In reinfected older adults, first boosters were still associated with lower hospitalization risk (adjusted-hazards-ratio, aHR = 0.55, 95% CI = 0.33–0.92) among the non-frail, but not in the intermediate/high-frailty-risk minority. Conclusions: First boosters were associated with reduced adverse COVID-19 outcomes across all frailty categories in infection-naïve older adults during Omicron. However, in the high-frailty minority, boosting did not additionally reduce risk in reinfected individuals with hybrid immunity, and beyond the first booster for infection-naïve individuals. Full article

Wastewater surveillance has proven to be a cost-effective, non-invasive method for monitoring the spread and evolution of SARS-CoV-2, yet its value during today’s low-incidence phase is still being defined. Between August 2023 and July 2024, 42 composite wastewater samples were collected in Perugia, Italy and analyzed using RT-qPCR and whole-genome sequencing to identify circulating SARS-CoV-2 lineages. In parallel, clinical samples (respiratory tract samples) were collected and analyzed, allowing for direct comparisons to confirm the robustness of the wastewater findings. The sewage viral loads ranged from 8.9 × 10⁵ to 4.9 × 10⁷ genome copies inhabitant⁻¹ day⁻¹, outlining two modest community waves (September–December 2023 and May–July 2024). Sequencing resolved 403 Omicron lineages and revealed three successive subvariant phases: (i) XBB.* dominance (August–October 2023), when late-Omicron XBB subvariants (mainly EG.5.* and XBB.1.5) accounted for almost all genomes; (ii) a BA.2.86/JN surge (November 2023–March 2024), during which the BA.2.86 subvariant, driven mainly by its JN descendants (especially JN.1), rapidly displaced XBB.* and peaked at 89% in February 2024; and (iii) KP.* takeover (April–July 2024), with JN.1-derived KP subvariants rising steadily and KP.3 reaching 81% by July 2024, thereby becoming the dominant lineage. Comparisons of data from wastewater and clinical surveillance demonstrated how the former presented a much higher diversity of circulating viral lineages. Importantly, some subvariants (including BA.2.86*) were detected in wastewater weeks to months prior to clinical identification, and for longer periods. Taken together, the obtained data validated wastewater surveillance as an effective early warning system, especially during periods of low infection prevalence and/or limited molecular testing efforts. This methodology can thus complement clinical surveillance by offering valuable insights into viral dynamics at the community level and enhancing pandemic preparedness. Full article

In this study, we conducted a comprehensive analysis of the interactions between the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein and four neutralizing antibodies—S309, S304, CYFN1006, and VIR-7229. Using integrative computational modeling that combined all-atom molecular dynamics (MD) simulations, mutational scanning, and MM-GBSA binding free energy calculations, we elucidated the structural, energetic, and dynamic determinants of antibody binding. Our findings reveal distinct dynamic binding mechanisms and evolutionary adaptation driving the broad neutralization effect of these antibodies. We show that S309 targets conserved residues near the ACE2 interface, leveraging synergistic van der Waals and electrostatic interactions, while S304 focuses on fewer but sensitive residues, making it more susceptible to escape mutations. The analysis of CYFN-1006.1 and CYFN-1006.2 antibody binding highlights broad epitope coverage with critical anchors at T345, K440, and T346, enhancing its efficacy against variants carrying the K356T mutation, which caused escape from S309 binding. Our analysis of broadly potent VIR-7229 antibody binding to XBB.1.5 and EG.5 Omicron variants emphasized a large and structurally complex epitope, demonstrating certain adaptability and compensatory effects to F456L and L455S mutations. Mutational profiling identified key residues crucial for antibody binding, including T345, P337, and R346 for S309 as well as T385 and K386 for S304, underscoring their roles as evolutionary “weak spots” that balance viral fitness and immune evasion. The results of the energetic analysis demonstrate a good agreement between the predicted binding hotspots, reveal distinct energetic mechanisms of binding, and highlight the importance of targeting conserved residues and diverse epitopes to counteract viral resistance. Full article

(1) Background: The currently circulating variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) exhibits resistance to antibodies induced by vaccines. The World Health Organization recommended the use of monovalent XBB.1 sublineages (e.g., XBB.1.5) as an antigenic component in 2023. (2) Objective: In this study, we aimed to develop vaccines based on the XBB.1.5 receptor-binding domain (RBD) to combat the recently emerged SARS-CoV-2 XBB and JN.1 variants, as well as previously circulating variants. (3) Methods: Glycoengineered Pichia pastoris was utilized to produce a recombinant XBB.1.5 RBD protein with mammalian-like and fucose-free N-glycosylation. The XBB.1.5 RBD was mixed with Al(OH)₃:CpG adjuvants to prepare monovalent vaccines. Thereafter, the XBB.1.5 RBD was mixed with the Beta (B.1.351), Delta (B.1.617.2), or Omicron (BA.2) RBDs (1:1 ratio), along with Al(OH)₃:CpG, to prepare bivalent vaccines. BALB/c mice were immunized with the monovalent and bivalent vaccines. Neutralizing antibody titers were assessed via pseudovirus and authentic virus assays; humoral immune responses were analyzed by RBD-binding IgG subtypes. (4) Results: The monovalent vaccine induced higher neutralizing antibody titers against Delta, BA.2, XBB.1.5, and JN.1 compared to those in mice immunized solely with Al(OH)₃:CpG, as demonstrated by pseudovirus virus assays. The XBB.1.5/Delta RBD and XBB.1.5/Beta RBD-based bivalent vaccines provided potent protection against the BA.2, XBB.1.5, JN.1, and KP.2 variants, as well as the previously circulating Delta and Beta variants. All monovalent and bivalent vaccines induced high levels of RBD-binding IgG (IgG1, IgG2a, IgG2b, and IgG3) antibodies in mice, suggesting that they elicited robust humoral immune responses. The serum samples from mice immunized with the XBB.1.5 RBD-based and XBB.1.5/Delta RBD-based vaccines could neutralize the authentic XBB.1.16 virus. (5) Conclusions: The XBB.1.5/Beta and XBB.1.5/Delta RBD-based bivalent vaccines are considered as potential candidates for broad-spectrum vaccines against SARS-CoV-2 variants. Full article

In the past 5 years, the COVID-19 pandemic has experienced frequently changing variants contextualizing immune evasion. The emergence of Omicron with >30–50 mutations on the spike gene has shown a sharp divergence from its relative VOCs, such as WT, Alpha, Beta, Gamma, and Delta. The requisition of prime boosting was essential within 3–6 months to improve the Nab response that had been not lasted for longer. Omicron subvariant BA.1.1 was less transmissible, but with an extra nine mutations in next variant BA.2 made it more transmissible. This remarkable heterogeneity was reported in ORF1ab or TRS sites, ORF7a, and 10 regions in the genomic sequences of Omicron BA.2 and its evolving subvariants BA.4.6, BF.7, BQ.2, BF. 7, BA.2.75.2, and BA.5 (BQ.1 and BQ.1.1). The mutational stability of subvariants XBB, XBB 1, XBB 1.5, and XBB 1.6 conferred a similar affinity towards ACE-2. This phenomenon has been reported in breakthrough infections and after booster vaccinations producing hybrid immunity. The reduced pathogenic nature of Omicron has implicated its adaptation either through immunocompromised individuals or other animal hosts. The binding capacity of RBD and ACE-2, including the proteolytic priming via TMPRSS2, reveals its (in-vitro) transmissibility behavior. RBD mutations signify transmissibility, S1/S2 enhances virulence, while S2 infers the effective immunogenic response. Initial mutations D614G, E484A, N501Y, Q493K, K417N, S477N, Y505H, and G496S were found to increase the Ab escape. Some mutations such as, R346K, L452R, and F486Vwere seen delivering immune pressure. HR2 region (S2) displayed mutations R436S, K444T, F486S, and D1199N with altered spike positions. Later on, the booster dose or breakthrough infections contributed to elevating the immune profile. Several other mutations in BA.1.1-N460K, R346T, K444T, and BA.2.75.2-F486S have also conferred the neutralization resistance. The least studied T-cell response in SARS-CoV-2 affects HLA- TCR interactions, thus, it plays a role in limiting the virus clearance. Antigenic cartographic analysis has also shown Omicron’s drift from its predecessor variants. The rapidly evolving SARS-CoV-2 variants and subvariants have driven the population-based immunity escape in fully immunized individuals within short period. This could be an indication that Omicron is heading towards endemicity and may evolve in future with subvariants could lead to outbreaks, which requires regular surveillance. Full article

SARS-CoV-2 remains a severe threat to worldwide public health, particularly as the virus continues to evolve and diversify into variants of concern (VOCs). Among these VOCs, Omicron variants exhibit unique phenotypic traits, such as immune evasion, transmissibility, and severity, due to numerous spike protein mutations and the rapid subvariant evolution. These Omicron subvariants have more than 15 mutations in the receptor-binding domain (RBD), a region of the SARS-CoV-2 spike protein that is important for recognition and binding with the angiotensin-converting enzyme 2 (ACE2) human receptor. To address the impact of these high numbers of Omicron mutations on the binding process, we have developed a novel method to precisely quantify amino acid interactions via the amino acid–amino acid bond pair (AABP). We applied this concept to investigate the interface interactions of the RBD–ACE2 complex in four Omicron Variants (BA.1, BA.2, BA.5, and XBB.1.16) with its Wild Type counterpart. Based on the AABP analysis, we have identified all the sites that are affected by mutation and have provided evidence that unmutated sites are also impacted by mutation. We have calculated that the binding between RBD and ACE2 is strongest in OV BA.1, followed by OV BA.2, WT, OV BA.5, and OV XBB.1.16. We also present the partial charge values for all 311 residues across these five models. Our analysis provides a detailed understanding of changes caused by mutation in each Omicron interface complex. Full article

Understanding the long-term dynamics of SARS-CoV-2 neutralizing antibodies is critical for evaluating vaccine-induced protection and informing booster strategies. In this longitudinal study, we analyzed 114 serum samples from 19 individuals across six time points over a three-year period following mRNA vaccination (Comirnaty) and natural SARS-CoV-2 infection. Using pseudotype-based neutralization assays against nine SARS-CoV-2 variants, including major Omicron subvariants (BA.1–BA.5, BQ.1.1, XBB), and anti-S1 IgG ELISA, we observed that antibody levels peaked after the third vaccine dose and remained relatively stable two years later. Neutralization titers rose markedly after the second and third doses, with the highest neutralization observed at two years post-booster. Strong correlations were found between anti-S1 IgG levels and mean neutralization titers for pre-Omicron variants (r = 0.79–0.93; p < 0.05), but only moderate for Omicron subvariants (r ≈ 0.50–0.64). Notably, hybrid immunity (vaccination plus infection) resulted in higher neutralization titers at the final time point compared to vaccine-only participants. The lowest neutralization was observed against XBB, underscoring the immune evasiveness of emerging variants. These findings support the importance of booster vaccination and highlight the added durability of hybrid immunity in long-term protection. Full article

Background/Objectives: The long-term effects of multiple updated vaccinations against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have not been clarified. Humoral or cellular immunity dynamics in healthcare workers for four years were analyzed. Methods: Blood samples were collected at five time points from April 2021 to January 2024. Humoral immunity was analyzed using the 50% neutralizing titer (NT₅₀) against the original Omicron XBB and Omicron BA.2.86 strains and cellular immunity were analyzed using the ELISpot interferon-gamma releasing assay. NT₅₀s and the spot-forming count (SFC) of the ELISpot assay were compared in the SARS-CoV-2 Omicron XBB-, Omicron-infected, and uninfected subjects. Results: 32 healthcare workers (median age, 47 years) who received 3–7 vaccine doses were enrolled. The NT₅₀s against the original strain decreased after the second vaccination but were maintained after the third vaccine dose. NT₅₀s against the Omicron XBB and BA.2.86 strains were detected before the Omicron vaccine was introduced and increased following the updated vaccination. The NT₅₀s against the Omicron XBB and BA.2.86 strains were elevated after natural infection by the Omicron strain, albeit without differences compared with the findings in uninfected subjects. Multivariate regression analysis revealed no confounder that affected the antibody titer against the BA.2.86 strain at the fifth blood sampling. The median number of SFCs ranged from 78 to 208 after the first two doses. Conclusions: Multiple vaccinations induced the production of antibodies with divergent activity against emerging mutant strains and enhanced protective effects against the original strain. This finding supported the importance of updated vaccination. Full article

The new Nuvaxovid protein-based and Pfizer-BioNTech mRNA-based vaccines targeting Omicron XBB.1.5 were available during the 2023–2024 autumn/winter vaccination campaign for frail individuals, including people with HIV (PWH). We assessed the immune response in 51 PWH on stable ART who received a booster with either the Nuvaxovid protein-based (n = 25) or Pfizer-BioNTech mRNA-based XBB.1.5 vaccine (n = 26). The median age was 57 years (IQR 51–65), the median count of CD4 at T0 was 652/mmc (503–935), and CD4 nadir was 226/mmc (95–340). Samples were collected before (T0) and one month after (T1) the booster. We measured neutralizing antibodies (nAbs) titers against D614G, XBB.1.6, and JN.1 variants and T-cell IFN-γ levels produced upon specific stimulation. Regardless of the vaccine used, we observed a marked increase in nAbs titers from T0 to T1 against all the subvariants, but no evidence for a change in IFN-γ release. After controlling for confounders, there was no evidence for a difference in the T0-T1 change in nAbs titers against XBB.1.16 and JN.1 by the type of vaccine, while Nuvaxovid determined a smaller increase in D614G nAbs (p = 0.008). The XBB.1.5 protein-based vaccine’s immunogenicity as a fifth or later booster was comparable to the Pfizer-BioNTech mRNA vaccine, particularly against recent Omicron variants. Full article

The global impact of the COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), persists in part due to the emergence of new variants. Understanding variant-specific infection dynamics and pathogenesis in murine models is crucial for identifying phenotypic changes and guiding the development of countermeasures. To address the limitations of earlier studies that investigated only a few variants or used small sample sizes, we evaluated clinical disease, infection kinetics, viral titers, cellular localization, and histopathologic changes in the lungs and brains of transgenic B6.Cg-Tg(K18-ACE2)2Prlmn/J (“K18”) and corresponding genetic control (C57BL/6J) mice expressing human angiotensin-converting enzyme 2 (hACE2). Six SARS-CoV-2 variants were assessed: B.1 (WA1-like), alpha, beta, delta, omicron, and omicron XBB.1.5, using cohorts of ≥18 mice. Following intranasal inoculation with B.1, alpha, beta, or delta variants, K18 mice experienced rapid weight loss and reached euthanasia criteria by 5–6 days post-inoculation (dpi). In contrast, K18 mice inoculated with both omicron variants recovered to their starting weight within 4–6 dpi. Infectious SARS-CoV-2 was detected in the oropharynx at 1 and2 dpi, in the lungs at 2, 4, and 6 dpi, and in the brain at 4 and 6 dpi for all variants except omicron. SARS-CoV-2 nucleoprotein was detected, and interstitial pneumonia of varying severity was observed in K18 mice infected with all variants. Brain lesions were identified in mice infected with the B.1, beta, and delta variants 6 dpi. As K18 mice express hACE2 in the brain—a feature not present in humans—we also compared infection dynamics of three variants to those of a mouse-adapted WA1 strain in C57BL/6J mice lacking the human ACE2 gene. C57BL/6J mice did not experience lethal disease, exhibited milder pneumonia, and had no evidence of neuroinvasion despite similar infection kinetics to K18 mice. These findings demonstrate contrasting phenotypes across the two models and reduced tropism and pathology of omicron compared to earlier variants in both models. This comprehensive analysis of SARS-CoV-2 variants in two mouse models provides valuable insights for model and variant selection for future studies. Full article

Background. The pathogenic coronaviruses (CoVs) MERS-CoV and SARS-CoV-2, which are responsible for the MERS outbreak and the COVID-19 pandemic, respectively, continue to infect humans, with significant adverse outcomes. There is a continuing need to develop mucosal vaccines against these respiratory viral pathogens to prevent entry and replication at mucosal sites. The receptor-binding domain (RBD) of the CoV spike (S) protein is a critical vaccine target, and glycan masking is a unique approach for designing subunit vaccines with improved neutralizing activity. Methods. We evaluated the efficacy of mucosal immunity, broad neutralizing activity, and cross-protection afforded by a combined glycosylated mucosal subunit vaccine encoding the RBDs of the original SARS-CoV-2 strain (SARS2-WT-RBD), the Omicron-XBB.1.5 variant (SARS2-Omi-RBD), and MERS-CoV (MERS-RBD). Results. Intranasal administration of the three-RBD protein cocktail induced effective, durable IgA and systemic IgG antibodies specific for the S protein of these CoVs, thereby neutralizing infection by pseudotyped SARS-CoV-2-WT, Omicron-XBB.1.5, and MERS-CoV. The mucosal vaccine cocktail protected immunized mice from challenge with SARS-CoV-2 Omicron-XBB.1.5 and MERS-CoV, leading to a significant reduction in the viral titers in the lungs. By contrast, the individual glycosylated RBD proteins only induced such immune responses and neutralizing antibodies against either SARS-CoV-2 or MERS-CoV, protecting against subsequent challenge with either SARS-CoV-2 or MERS-CoV; they did not provide simultaneous protection against both CoVs. Conclusions. This study describes a unique strategy for designing efficacious mucosal subunit vaccines that induce durable mucosal immunity, cross-neutralizing activity, and cross-protection against SARS-CoV-2 and MERS-CoV, highlighting the potential for the design of mucosal vaccines against other pathogens. Full article