They tested people to check for evidence of asymptomatic infection and found that people who had two doses of the nasal vaccine showed no signs of infection after three months.

CONCLUSION. A 2-dose intranasal vaccination regimen using NB2155 was safe, was well tolerated, and could dramatically induce broad-spectrum spike-specific sIgA in the nasal passage. Preliminary data suggested that the intranasal vaccination may establish an effective mucosal immune barrier against infection and warranted further clinical studies.

https://insight.jci.org/articles/view/180784

"At least 86.2% participants who completed 2 [nasal vaccine] doses maintained uninfected status, likely without even asymptomatic infection, for at least 3 months.

https://xcancel.com/EricTopol/status/1838937705977110991#m

Seems like we are getting closer to better vaccines being approved.