biostudies-literatureCai JPRichard Yu and Carol Yu, Michael Seak-Kan Tong, May Tam Mak Mei Yin, the Lee Wan Keung Charity Foundation LimitedEmergency COVID-19 ProjectChan Yin Chuen Memorial Charitable FoundationKai Chong Tong, Tse Kam Ming Laurence, the Foo Oi Foundation LimitedMajor Science and Technology Program of Hainan ProvincePerfect Shape Medical Limitedresearch project of Hainan Academician Innovation PlatformHui Ming, Hui Hoy and the Chow Sin Lan Charity Fund LimitedResearch Grants Council of the Hong Kong Special Administrative RegionHealth and Medical Research FundCollaborative Research FundHong Kong Sanatorium and HospitalMarina Man-Wai Lee, the Hong Kong Hainan Commercial Association South China Microbiology Research FundHainan Talent Development ProjectChen Wai Wai Vivien Foundation LimitedProvidence Foundation LimitedShaw Foundation Hong KongEmergency Collaborative Project of Guangzhou LaboratoryBetty Hing-Chu Lee, Ping Cham So, and the Lo Ying Shek Chi Wai FoundationJessie and George Ho Charitable FoundationHealth@InnoHK687https://www.ebi.ac.uk/biostudies/studies/S-EPMC10052291biostudies-literatureUnknown15(3)The emergence of new immune-evasive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and subvariants outpaces the development of vaccines specific against the dominant circulating strains. In terms of the only accepted immune correlate of protection, the inactivated whole-virion vaccine using wild-type SARS-CoV-2 spike induces a much lower serum neutralizing antibody titre against the Omicron subvariants. Since the inactivated vaccine given intramuscularly is one of the most commonly used coronavirus disease 2019 (COVID-19) vaccines in developing regions, we tested the hypothesis that intranasal boosting after intramuscular priming would provide a broader level of protection. Here, we showed that one or two intranasal boosts with the Fc-linked trimeric spike receptor-bVirusesIntranasal Boosting with Spike Fc-RBD of Wild-Type SARS-CoV-2 Induces Neutralizing Antibodies against Omicron Subvariants and Reduces Viral Load in the Nasal Turbinate of Mice.PMC10052291YSPTZX202004C7060-21G2021YFC0866100ZDKJ202003SRC200003T11-709/21-NCOVID1903010–Projects 7EKPG22-01Cai JPYuan SCao HJin DYZhang AJChan JFChen LLHan YChen HLuo CWang KYin FChen ZZhang XTo KKChu HYuen KYKok KHfalseIntranasal Boosting with Spike Fc-RBD of Wild-Type SARS-CoV-2 Induces Neutralizing Antibodies against Omicron Subvariants and Reduces Viral Load in the Nasal Turbinate of Mice.The emergence of new immune-evasive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and subvariants outpaces the development of vaccines specific against the dominant circulating strains. In terms of the only accepted immune correlate of protection, the inactivated whole-virion vaccine using wild-type SARS-CoV-2 spike induces a much lower serum neutralizing antibody titre against the Omicron subvariants. Since the inactivated vaccine given intramuscularly is one of the most commonly used coronavirus disease 2019 (COVID-19) vaccines in developing regions, we tested the hypothesis that intranasal boosting after intramuscular priming would provide a broader level of protection. Here, we showed that one or two intranasal boosts with the Fc-linked trimeric spike receptor-b2023-01-01T00:00:00Z2023 Mar2026-05-14T03:09:20.052Z2024-11-05T18:16:18.934ZS-EPMC100522913699239510.3390/v15030687