Sanofi is the largest company devoted entirely to vaccines and is currently running a Phase I/II clinical trial on 6 different formulations of HSV529, G103, and an adjuvant.
HSV529 is a replication-defective vaccine while G103 is a subunit vaccine. In a Phase I trial completed in 2018, HSV529 induced a statistically significant increase in antibody titers for participants who were both positive and negative for HSV.
In a preclinical trial in guinea pigs in 2016, G103 was able to effectively reduce both symptoms and shedding by 50%.
The current Phase I/II clinical trial is looking at different combinations and formulations of HSV529, G103, and an adjuvant in order to find the optimal dose in eliminating outbreaks and shedding.
Phase I completed in May 2021 and Sanofi has a estimated completion date for Phase II in May 2024. This suggests Phase I has shown safety/potential efficacy and recruitment for Phase II is estimated to start end of 2022.