Four groups of mice and four groups of hamsters received two intranasal immunizations on day one and day 21. One group of mice and hamsters received a vaccine based on OMV mixed with rSp (CovOMV), and the other was given a vaccine based on OMV coupled to rSp based on Intravacc's proprietary OMV click technology (CovOMVclick). Blood samples were taken, bodyweight loss was measured, and they were examined for lung lesions on day seven.

In the mice that received the CovOMV, 30% virus neutralizing antibodies were detected. Meanwhile, 90% virus neutralizing antibodies were found in those that received CovOMVclick. Both vaccine candidates induced neutralizing antibodies in hamsters, but levels of antibodies were slightly higher in the animals that received CovOMVclick. Since no lung lesions were detected, intranasal vaccination with both OMV-rSp vaccine candidates resulted in complete protection, according to Intravacc.

These preclinical results will allow the company to quickly advance to a phase I/II clinical trial.