The multicenter, dose finding Phase 1/2 study starts off with an open-label, dose-escalation part, thereafter, during the double-blind part of study, participants will be randomized 1:1:1 to receive the low, medium or high dose of the vaccine (VLA2001). All participants will received a total of two vaccinations intramuscularly, on day 1 and day 22.
The first 5 participants in each dose group will receive VLA2001 open label, starting with the low dose of VLA2001. If no safety concerns are identified, the next 5 subjects will receive the medium dose of the vaccine. Again, if no safety issues are identified, 5 participants will be vaccinated with the high dose vaccine. A Data Safety and Monitoring Board (DSMB) will review accrued safety data before randomization of the remaining 135 subjects across all sites will be initiated.
All study participants will be followed up for safety and immunogenicity up to approximately 6 months after receiving their second vaccination.
April 6, 2021 - Positive data for Part A of the Phase 1/2 clinical trial of its inactivated, adjuvanted COVID-19 vaccine candidate, VLA2001. Based on this data, the Company plans to commence a Phase 3 clinical trial by the end of April 2021, subject to regulatory approval.
VLA2001 was generally well tolerated across all dose groups tested, with no safety concerns identified by an independent Data Safety Monitoring Board. There were no statistically significant differences between dose groups and no differences between first and second vaccinations in terms of reactogenicity. The majority of Adverse Events (AEs) were mild or moderate and only two subjects reported severe solicited AEs (headache and fatigue). All solicited AEs were transient. Only 17.6% of unsolicited AEs up to day 36 were considered related to the vaccine and no severe unsolicited AEs were reported. No serious related AEs were reported.
VLA2001 was highly immunogenic with more than 90% of all study participants developing significant levels of antibodies to the SARS-CoV-2 virus spike protein across all dose groups tested. Seroconversion Rates (SCR) for S-protein binding IgG antibodies were 89.8% in the medium-dose and 100% in the high dose group. Two weeks after completion of the two-dose schedule, Geometric Mean Fold Rise (GMFR) from baseline was 26 in the medium-dose and 86 in the high dose group.
Of note, the IgG antibody response was highly correlated with neutralization titers in a micro-neutralization assay (MNA50) (r=0.79, p<0.001).