Emergent BioSolutions Inc. and Valneva SE announced this week positive interim results for the Phase 1 study evaluating VLA1601, their vaccine candidate against the Zika virus.


The highly purified inactivated vaccine candidate, VLA1601, met the study’s primary endpoint showing a favorable safety profile in all doses and schedules tested.

VLA1601 was also immunogenic in all treatment groups and induced both dose- and schedule- dependent neutralizing antibodies against the Zika virus with the kinetics expected for an inactivated, alum-adjuvanted whole-virus vaccine. Seroconversion Rates (SCR) reached up to 85.7% on Day 35 (Interim Analysis of Data up to Day 56).

The Phase 1 study was designed to assess safety and immunogenicity.

Wolfgang Bender, MD, PhD, chief medical officer of Valneva commented, “We are pleased to see progress of this promising vaccine candidate for the prevention of infections caused by the Zika virus and their serious implications during pregnancy. The excellent safety profile supports further optimization of the elicited immune response to cover an unmet medical need in the most vulnerable populations.”

The Zika virus is a mosquito-borne flavivirus that was first discovered in 1947. The first human cases were detected in 1952. Since then, outbreaks have been reported in tropical Africa, Southeast Asia, the Pacific Islands, and, in 2015, in the Americas.

According to the World Health Organization, there is scientific consensus that ZIKV is a cause of microcephaly and Guillain-Barré syndrome. Since 2013, 31 countries and territories have reported cases of microcephaly and other central nervous system malformations associated with ZIKV infection.