Abstract
Respiratory viral infections, such as influenza and coronavirus, are major threats to humankind. Injectable vaccines for SARS-CoV-2 protect against severe disease but fail to induce immunity in the upper airway mucosa, the virus entry site, thus not preventing infection and transmission. This highlights the urgent need for mucosal-targeted vaccination systems. While intranasal immunization holds promise, achieving local antigen delivery for mucosal immunity remains challenging. To address this, we designed an innovative nanoparticle system to deliver intranasal vaccines, using the receptor-binding domain (RBD) and multiple T-cell epitopes of SARS-CoV-2 antigens. Nonporous silica-based nanoparticles (SiNP) functionalized with a mucoadhesive cyclodextrin polymer (MaP) were selected as a delivery vehicle capable of adhering to and penetrating mucus. In a 3-dose regimen, the nanovaccine induced and sustained high systemic and neutralizing antibody levels for at least 1 year, with robust cellular responses, as well as IgA secretion in the oral and nasal cavities, providing strong protection against SARS-CoV-2 and substantially reducing viral loads in both upper and lower respiratory tracts. Our findings provide evidence that an intranasal vaccination platform combining two distinct nanoscale strategies might be crucial for inducing lasting and broad systemic and upper airway immunity, potentially controlling SARS-CoV-2 infection and transmission.
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Data availability
The datasets generated and/or analyzed during the current study are not publicly available due to our institution does not maintain open-access data repositories and primary records are stored in secure institutional laboratory archives. All key data are provided in the Source Data file, and additional datasets are available from the corresponding author on reasonable request.
References
World Health Organization. The top 10 causes of death https://www.who.int/news-room/fact-sheets/detail/the-top-10-causes-of-death (2020).
World Health Organization. COVID-19 vaccine tracker and landscape https://www.who.int/publications/m/item/draft-landscape-of-covid-19-candidate-vaccines (2023).
Shang, J. et al. Structural basis of receptor recognition by SARS-CoV-2. Nature 581, 221–224 (2020).
Wrapp, D. et al. Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation. Science 367, 1260–1263 (2020).
Bourgonje, A. R. et al. Angiotensin-converting enzyme 2 (ACE2), SARS-CoV-2 and the pathophysiology of coronavirus disease 2019 (COVID-19). J. Pathol. 251, 228–248 (2020).
Mohammed, I. et al. The efficacy and effectiveness of the COVID-19 vaccines in reducing infection, severity, hospitalization, and mortality: a systematic review. Hum. Vaccin. Immunother. 18, 2027160 (2022).
Bleier, B. S., Ramanathan, M. & Lane, A. P. COVID-19 vaccines may not prevent nasal SARS-CoV-2 infection and asymptomatic transmission. Otolaryngol. Head. Neck Surg. 164, 305–307 (2020).
Liew, F. et al. SARS-CoV-2-specific nasal IgA wanes 9 months after hospitalisation with COVID-19 and is not induced by subsequent vaccination. EBioMedicine 87, 104402 (2023).
Fröberg, J. et al. SARS-CoV-2 mucosal antibody development and persistence and their relation to viral load and COVID-19 symptoms. Nat. Commun. 12, 5621 (2021).
Pilapitiya, D., Wheatley, A. K. & Tan, H.-X. Mucosal vaccines for SARS-CoV-2: triumph of hope over experience. EBioMedicine 92, 104585 (2023).
Kehagia, E., Papakyriakopoulou, P. & Valsami, G. Advances in intranasal vaccine delivery: a promising non-invasive route of immunization. Vaccine 41, 3589–3603 (2023).
Slomski, A. Intranasal COVID-19 vaccine disappointing in first-in-human trial. JAMA 328, 2003 (2022).
Zhu, F. et al. Safety and efficacy of the intranasal spray SARS-CoV-2 vaccine dNS1-RBD: a multicentre, randomised, double-blind, placebo-controlled, phase 3 trial. Lancet Respir. Med. 11, 1075–1088 (2023).
Sun, B. et al. An intranasally administered adenovirus-vectored SARS-CoV-2 vaccine induces robust mucosal secretory IgA. JCI Insight 9, e180784 (2024).
Ndzouboukou, J. B., Kamara, A. A., Ullah, N., Lei, Q. & Fan, X. L. A Meta-analysis on the immunogenicity of homologous versus heterologous immunization regimens against SARS-CoV-2 Beta, Delta, and Omicron BA.1 VoCs in healthy adults. J. Microbiol. Biotechnol. 35, e2411059 (2025).
Nissilä, E. et al. The COVID-19 vaccine ChAdOx1 is opsonized by anti-vector antibodies that activate complement and promote viral vector phagocytosis. Scand. J. Immunol. 101, e70000 (2025).
Yang, Y., Zhang, M., Song, H. & Yu, C. Silica-based nanoparticles for biomedical applications: from nanocarriers to biomodulators. Acc. Chem. Res. 53, 1545–1556 (2020).
Liljenström, C.L.D.; Finnveden, G. Silicon-Based Nanomaterials in a Life-Cycle Perspective, Including a Case Study on SelfCleaning Coatings https://www.researchgate.net/publication/280264076_Silicon-based_nanomaterials_in_a_life-cycle_perspective_including_a_case_study_on_self-cleaning_coatings (2013).
Tang, L. & Cheng, J. Nonporous silica nanoparticles for nanomedicine application. Nano Today 8, 290–312 (2013).
Janjua, T. I., Cao, Y., Yu, C. & Popat, A. Clinical translation of silica nanoparticles. Nat. Rev. Mater. 6, 1072–1074 (2021).
Tan, A., Eskandar, N. G., Rao, S. & Prestidge, C. A. First in man bioavailability and tolerability studies of a silica–lipid hybrid (Lipoceramic) formulation: a Phase I study with ibuprofen. Drug Deliv. Transl. Res. 4, 212–221 (2014).
Meola, T. R., Abuhelwa, A. Y., Joyce, P., Clifton, P. & Prestidge, C. A. A safety, tolerability, and pharmacokinetic study of a novel simvastatin silica-lipid hybrid formulation in healthy male participants. Drug Deliv. Transl. Res. 11, 1261–1272 (2021).
Barandeh, F. et al. Organically modified silica nanoparticles are biocompatible and can be targeted to neurons in vivo. PLoS ONE 7, e29424 (2012).
Brown, S. C. et al. Influence of shape, adhesion and simulated lung mechanics on amorphous silica nanoparticle toxicity. Adv. Powder Technol. 18, 69–79 (2007).
Fruijtier-Pölloth, C. The toxicological mode of action and the safety of synthetic amorphous silica-a nanostructured material. Toxicology 294, 61–79 (2012).
Yu, T., Greish, K., McGill, L. D., Ray, A. & Ghandehari, H. Influence of geometry, porosity, and surface characteristics of silica nanoparticles on acute toxicity: their vasculature effect and tolerance threshold. ACS Nano 6, 2289–2301 (2012).
European Medicines Agency, Scientific Committee on Consumer Safety opinion on silica, hydrated silica, and silica surface modified with alkyl silicates (nano form) https://ec.europa.eu/health/scientific_committees/consumer_safety/docs/sccs_o_175.pdf (2015).
U.S Food and Drug Administration, US Food and Drug Administration GRAS Substances (SCOGS) Database—Select Committee on GRAS Substances (SCOGS) Opinion: Silicates, (n.d.) https://www.fda.gov/food/generally-recognized-safe-gras/gras-substances-scogs-database (2022).
FDA, 2023 U.S. FDA Drug Master Files (DMF) 1Q2023 https://www.fda.gov/media/166951/download (2023).
EMA, 2017 Cyclodextrins used as excipients. Report published in support of the ‘Questions and answers on cyclodextrins used as excipients in medicinal products for human use’ (EMA/CHMP/495747/2013) https://www.ema.europa.eu/en/documents/scientific-guideline/questions-and-answers-cyclodextrins-used-excipients-medicinal-products-human-use_en.pdf (2017).
Rassu, G. et al. Versatile nasal application of cyclodextrins: excipients and/or actives. Pharmaceutics 13, 1180 (2021).
Marttin, E., Verhoef, J. C. & Merkus, F. W. Efficacy, safety and mechanism of cyclodextrins as absorption enhancers in nasal delivery of peptide and protein drugs. J. Drug Target. 6, 17–36 (1998).
Asim, M. H. et al. S-protected thiolated cyclodextrins as mucoadhesive oligomers for drug delivery. J. Colloid Interface Sci. 531, 261–268 (2018).
Jansook, P., Ogawa, N. & Loftsson, T. Cyclodextrins: structure, physicochemical properties and pharmaceutical applications. Int. J. Pharm. 535, 272–284 (2018).
Haimhoffer, A. et al. Cyclodextrins in drug delivery systems and their effects on biological barriers. Sci. Pharm. 87, 33 (2019).
Matassoli, F. L. et al. Hydroxypropyl-beta-cyclodextrin reduces inflammatory signaling from monocytes: possible implications for suppression of HIV chronic immune activation. mSphere 3, e00497–18 (2018).
Lu, A. et al. Hydroxypropyl-beta cyclodextrin barrier prevents respiratory viral infections: a preclinical study. Int. J. Mol. Sci. 25, 2061 (2024).
Asai, K. et al. The effects of water-soluble cyclodextrins on the histological integrity of the rat nasal mucosa. Int. J. Pharm. 246, 25–35 (2002).
Agu, R. U. et al. Safety assessment of selected cyclodextrin-effect of ciliary activity using a human cell suspension culture model exhibiting in-vitro ciliogenesis. Int. J. Pharm. 193, 219–226 (2000).
Yuan, M., Liu, H., Wu, N. C. & Wilson, I. A. Recognition of the SARS-CoV-2 receptor binding domain by neutralizing antibodies. Biochem. Biophys. Res. Commun. 538, 192–203 (2021).
Fernandes, E. R. et al. Time-dependent contraction of the SARS-CoV-2-specific T-cell responses in convalescent individuals. JACI Glob. 1, 112–121 (2022).
Ichinohe, T. et al. Synthetic double-stranded RNA poly(I:C) combined with mucosal vaccine protects against influenza virus infection. J. Virol. 79, 2910–2919 (2005).
Sloat, B. R. & Cui, Z. Nasal immunization with anthrax protective antigen protein adjuvanted with polyriboinosinic-polyribocytidylic acid-induced strong mucosal and systemic immunities. Pharm. Res. 23, 1217–1226 (2006).
Netsomboon, K. & Bernkop-Schnürch, A. Mucoadhesive vs. mucopenetrating particulate drug delivery. Eur. J. Pharm. Biopharm. 98, 76–89 (2016).
Corr, S. C., Gahan, C. C. G. M. & Hill, C. M-cells: origin, morphology and role in mucosal immunity and microbial pathogenesis. FEMS Immunol. Med. Microbiol. 52, 2–12 (2008).
Kiyono, H. & Fukuyama, S. NALT- versus Peyer’s-patch-mediated mucosal immunity. Nat. Rev. Immunol. 4, 699–710 (2004).
Gómez, D. M., Urcuqui-Inchima, S. & Hernandez, J. C. Silica nanoparticles induce NLRP3 inflammasome activation in human primary immune cells. Innate Immun. 23, 697–708 (2017).
Tang, L., Fan, T. M., Borst, L. B. & Cheng, J. Synthesis and biological response of size-specific, monodisperse drug-silica nanoconjugates. ACS Nano 6, 3954–3966 (2012).
Hirai, T. et al. Amorphous silica nanoparticles enhance cross-presentation in murine dendritic cells. Biochem. Biophys. Res. Commun. 427, 553–556 (2012).
Vis, B. et al. Non-functionalized ultrasmall silica nanoparticles directly and size-selectively activate T cells. ACS Nano 12, 10843–10854 (2018).
Onishi, M. et al. Hydroxypropyl-beta-cyclodextrin spikes local inflammation that induces Th2 cell and T follicular helper cell responses to the coadministered antigen. J. Immunol. 194, 2673–2682 (2015).
Sanità, G., Carrese, B. & Lamberti, A. Nanoparticle surface functionalization: how to improve biocompatibility and cellular internalization. Front. Mol. Biosci. 7, 587012 (2020).
Button, B. et al. A periciliary brush promotes the lung health by separating the mucus layer from airway epithelia. Science 337, 937–941 (2012).
de Steenhuijsen Piters, W. A. A. et al. Interaction between the nasal microbiota and S. pneumoniae in the context of live-attenuated influenza vaccine. Nat. Commun. 10, 2981 (2019). 9.
Liu, X., Wetzler, L. M., Nascimento, L. O. & Massari, P. Human airway epithelial cell responses to Neisseria lactamica and purified porin via Toll-like receptor 2-dependent signaling. Infect. Immun. 78, 5314–5323 (2010).
de Fays, C., Carlier, F. M., Gohy, S. & Pilette, C. Secretory immunoglobulin A immunity in chronic obstructive respiratory diseases. Cells 11, 1324 (2022).
Firacative, C. et al. Identification of T helper (Th)1- and Th2-associated antigens of Cryptococcus neoformans in a murine model of pulmonary infection. Sci. Rep. 8, 2681 (2018).
Khoury, D. S. et al. Measuring immunity to SARS-CoV-2 infection: comparing assays and animal models. Nat. Rev. Immunol. 20, 727–738; 1 (2020).
Liu, C., Jiang, X., Gan, Y. & Yu, M. Engineering nanoparticles to overcome the mucus barrier for drug delivery: design, evaluation and state-of-the-art. Med. Drug Discov. 12, 100110 (2021).
Honary, S. & Zahir, F. Effect of zeta potential on the properties of nano-drug delivery systems - A review (Part 1). Trop. J. Pharm. Res. 12, 255–264 (2013).
Foroozandeh, P. & Aziz, A. A. Insight into cellular uptake and intracellular trafficking of nanoparticles. Nanoscale Res. Lett. 13, 339 (2018).
Newby, J. M. et al. Technologies strategies to estimate and control diffuse passage times through the mucus barrier in mucosal drug delivery. Adv. Drug Deliv. Rev. 124, 64–81 (2018).
Li, M. et al. Enhanced intranasal delivery of mRNA vaccine by overcoming the nasal epithelial barrier via intra- and paracellular pathways. J. Control. Release 228, 9–19 (2016).
Li, L. et al. Biodistribution, excretion, and toxicity of mesoporous silica nanoparticles after oral administration depend on their shape. Nanomedicine 11, 1915–1924 (2015).
He, X. X. et al. In vivo study of biodistribution and urinary excretion of surface-modified silica nanoparticles. Analy. Chem. 80, 9597–9603 (2008).
Choi, H. S. et al. Renal clearance of nanoparticles. Nat. Biotechnol. 25, 1165–1170 (2009).
Arick, D. Q., Choi, Y. H., Kim, H. C. & Won, Y.-Y. Effects of nanoparticles on the mechanical functioning of the lung. Adv. Colloid Interface Sci. 225, 218–228 (2015).
Gu, X. et al. Clearance of two organic nanoparticles from the brain via the paravascular pathway. J. Control. Rel. 322, 31–41 (2020).
Formica, M. L. et al. On a highway to the brain: a review on nose-to-brain drug delivery using nanoparticles. Appl. Mater. Today 29, 101631 (2022).
Hajdu, I. et al. Radiochemical synthesis and preclinical evaluation of 68Ga-labeled NODAGA-hydroxypropyl-beta-cyclodextrin (68Ga-NODAGA-HPBCD). Eur. J. Pharm. Sci. 128, 202–208 (2019).
Carter, N. J. & Curran, M. P. Live attenuated influenza vaccine (Flumist; Fluenz): a review of its use in prevention of seasonal influenza in children and adults. Drugs 71, 1591–1622 (2011).
Mutsch, M. et al. Use of the inactivated intranasal influenza vaccine and the risk of Bell’s palsy in Switzerland. N. Engl. J. Med. 350, 896–903 (2004).
Madhavan, M. et al. Tolerability and immunogenicity of an intranasally-administered adenovirus-vectored COVID-19 vaccine: an open-label partially-randomised ascending dose phase I trial. EBioMedicine 85, 104298 (2022).
Knudsen, K. B. et al. In vivo toxicity of cationic micelles and liposomes. Nanomedicine 11, 467–477 (2015).
Zhang, P. et al. Nanoparticle size influences antigen retention and presentation in lymph node. ACS Nano 9, 8480–8493 (2015).
Southam, D. S., Dolovich, M., O’Byrne, P. M. & Inman, M. D. Distribution of intranasal instillations in mice: effects of volume, time, body position, and anesthesia. Am. J. Physiol. Lung Cell Mol. Physiol. 282, L833–L839 (2002).
Mitchell, M. J. et al. Engineering precision nanoparticles for drug delivery. Nat. Rev. Drug Discov. 20, 101–124 (2021).
Corthésy, B. Role of secretory IgA in infection and immunity. Mucosal Immunol. 6, 535–542 (2013).
Wright, P. F. et al. Longitudinal systemic and mucosal immune response to SARS-CoV-2 infection. J. Infect. Dis. 226, 1204–1214 (2022).
Hartwell, B. L. et al. Intranasal vaccination with lipid-conjugated immunogens promotes antigen transmucosal uptake to drive mucosal and systemic immunity. Sci. Transl. Med. 14, eabn1413 (2022).
Adhikari, K. & Verma, S. C. Neutralization antibody responses to SARS-CoV-2 variants after COVID-19 vaccination and boosters. Vaccine 24, 100664 (2025).
Bladh, O. et al. Comparison of SARS-CoV-2 spike-specific IgA and IgG in nasal secretions, saliva and serum. Front. Immunol. 15, 1346749 (2024).
Riepler, L. et al. Comparison of four SARS-CoV-2 neutralization assays. Vaccines 9, 13 (2020).
Klein, S. L. & Flanagan, K. L. Sex differences in immune responses. Nat. Rev. Immunol. 16, 626–638 (2016).
Huang, L.-Y., Stuart, C., Takeda, K., D’Agnillo, F. & Golding, B. Poly(I:C) induces human lung endothelial barrier dysfunction by disrupting tight junction expression of claudin-5. PloS One 11, e0160875 (2016).
Starkhammar, M. et al. Intranasal administration of poly(I:C) and LPS in BALB/c mice induces airway hyperresponsiveness and inflammation via different pathways. PLoS ONE 7, e32110 (2012).
Misra, S. K., Kapoor, A. & Pathak, K. Nanovaccines for Mucosal Immunity (eds Chavda, V. P. & Apostolopoulos, V.) 367–404 (Wiley online library, 2024).
WHO. Recommendations to assure the quality, safety and efficacy of influenza vaccines (human, live attenuated) for intranasal administration, Annex 4, WHO Technical Report Series No. 977 https://www.who.int/publications/m/item/influenza-attenuated-intranasal-administration-annex-4-trs-no-977 (2013).
Nair, A. B. & Jacob, S. A simple practice guide for dose conversion between animals and human. J. Basic Clin. Pharm. 7, 27–31 (2016).
Đorđević, S. et al. Current hurdles to the translation of nanomedicines from bench to the clinic. Drug Deliv. Transl. Res. 12, 500–525; 2 (2022).
Stöber, W., Fink, A. & Bohn, E. Controlled growth of monodisperse silica spheres in the micron size range. J. Colloid Interface Sci. 26, 62–69 (1968).
Severe Acute Respiratory Syndrome Coronavirus 2 Isolate Wuhan-Hu-1, co-Nucleotide-NCBI. https://www.ncbi.nlm.nih.gov/nuccore/MN908947 (2020).
Dai, L. et al. Universal design of Betacoronavirus vaccines against COVID-19, MERS, and SARS. Cell 182, 722–733 (2020).
Stadlbauer, D. et al. SARS-CoV-2 seroconversion in humans: a detailed protocol for a serological assay, antigen production, and test setup. Curr. Protoc. Microbiol. 57, e100 (2020).
Araújo, D. B. et al. SARS-CoV-2 isolation from the first reported patients in Brazil and establishment of a coordinated task network. Mem. Inst. Oswaldo Cruz 115, e200342 (2020).
World Health Organization (WHO). Laboratory Biosafety Guidance Related to the Novel Coronavirus (2019-nCoV). https://www.who.int/docs/default-source/coronaviruse/laboratory-biosafety-novelcoronavirus-version-1-1.pdf?sfvrsn=912a9847_2 (WHO, 2020).
Whittaker, A. L., Liu, Y. & Barker, T. H. Methods used and application of the mouse Grimace Scale in biomedical research 10 years on: a scoping review. Animals 11, 673 (2021).
Schmidt, F. et al. Measuring SARS-CoV-2 neutralizing antibody activity using pseudotyped and chimeric viruses. J. Exp. Med. 217, e20201181 (2020).
Quiros, P. M., Goyal, A., Jha, P. & Auwerx, J. Analysis of mtDNA/nDNA ratio in mice. Curr. Protoc. Mouse Biol. 7, 47–54 (2017).
Acknowledgements
The authors would like to thank Dr. Paul Bieniasz from Rockefeller University for providing the materials for carrying out the pseudovirus neutralization tests and Dr. Carsten Wrenger and Dr. Edmarcia de Souza from Institute of Biomedical Sciences, Universidade de São Paulo, for providing the BSL3 facilities. And on behalf of Ms. Jhosiene Magawa, from Instituto do Coração, Hospital das Clínicas. This work was supported by FINEP [grant number 01.20.0009.00], CNPq [grant numbers 403701/2020-1, 403520/2020-7, and 408518/2022-7], and DECEIIS/SECTICS/MS [grant number 25000.177752/2022-11].
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R.L.P. developed the study, conducted preclinical assays and cellular immune response experiments, analyzed the data, and wrote the manuscript. Y.S.S., E.P., and R.E.A. performed preclinical assays and humoral immune response experiments. M.A.S., M.C.K., K.A., J.J.S., C.R., and S.H.T. produced and characterized the nanovaccine. A.M., T.L.S., S.B.B., I.P.D., A.M.M., and J.V.B.-C. contributed to the production of proteins and pseudoviruses and performed pseudoviral neutralization assays. J.P.S.N. carried out viral RNA quantification. L.M.D. performed histopathological analyses. E.C.-N., L.C.J., D.S.R., K.S.S., and V.C. selected and designed the peptides included in the vaccine formulation, project administration, data validation, and funding acquisition. V.O. served as project manager and contributed to funding acquisition. J.K. conceptualized the study, supervised the project, and secured funding. All authors read and approved the final manuscript.
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Pagni, R.L., Cunha-Neto, E., Silva Santos, Y.d. et al. An innovative nasal nanovaccine against SARS-CoV-2 induces systemic and upper airway immunity controlling viral replication. npj Vaccines (2026). https://doi.org/10.1038/s41541-026-01407-x
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DOI: https://doi.org/10.1038/s41541-026-01407-x
