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The Ad5-S-Omicron intranasal vaccine demonstrates good safety and immunogenicity, with a second dose significantly enhancing nasal spike-specific sIgA, providing effective protection against Omicron infections.
According to a study published in “JCI Insight” journal, a two-dose intranasal vaccine, Ad5-S-Omicron (NB2155) increased spike-specific secretory immunoglobulin A (sIgA) in the nasal passages to considerable levels. As inferred from previous research, the higher levels of nasal spike-specific secretory IgA were linked with a lower risk of SARS-CoV-2 Omicron infections. This open-label, single-centre trial by Baoqing Sun et al. aimed to assess the safety and immunogenicity of NB2155, a replication-incompetent adenovirus designed to carry the Omicron BA.1 spike protein.
One hundred and twenty-eight healthcare workers who had not been previously infected with SARS-CoV-2 and had received 2 or 3 doses of inactivated whole-virus vaccines (administered 3 to 19 months prior) were enrolled. Administration of 2 intranasal sprays of NB2155 spaced 28 days apart was done. Safety was observed by tracking adverse events and conducting laboratory tests. The study also evaluated the rise of nasal mucosal spike-specific sIgA and serum-neutralizing antibodies. Mild solicited adverse events connected to the vaccine were noted.
The nasal spike-specific sIgA levels against 10 strains surged by a geometric mean fold of 4.5 after the first dose, while a dramatic rise to 51.5 was found after the second dose. By day 14 post-second dose, the serum neutralizing titers also rose modestly, reaching 128.1 against the authentic BA.1 strain and 76.9 against BA.5. About 57.3% of participants had BA.5 infections between 15 and 28 days post-first dose after China's 'Zero-COVID' guideline ended in December 2022. However, no symptomatic infections occurred between 3 and 90 days after the second dose, and tests confirmed no asymptomatic infections during the trial. Thus, intranasal vaccination may efficiently bolster mucosal immunity against infections, paving the way for more extensive clinical studies.
JCI Insight
An intranasally administered adenovirus-vectored SARS-CoV-2 vaccine induces robust mucosal secretory IgA
Baoqing Sun et al.
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