Safety and Immunogenicity of Inactivated Heterologous Booster Vaccination

Data from some studies indicate the decline in the effectiveness of the authorized COVID-19 vaccines due to antibody waning following vaccination and the emergence of different variants. These findings support the need to increase vaccination and booster campaigns to protect the adult population against infection. Valneva developed the VLA2001 vaccine, a highly purified, whole virus SARS-CoV-2 vaccine produced on Vero cells and inactivated with β-propiolactone. VLA2001 will be adjuvanted with the licensed adjuvant cytosine phospho-guanine (CpG) 1018 (produced by Dynavax, contained in HEPLISAV-B®) in combination with aluminum hydroxide. On April 14, 2022, VLA2001 was granted Conditional Marketing Authorization (CMA) by the Medicines and Healthcare products Regulatory Agency (MHRA) of the United Kingdom for primary immunization in adults 18 to 50 years of age. This follows the emergency use authorization granted by the Bahraini NHRA in March 2022. As a substantial population has received a primary vaccination series with authorized vaccines, a booster dose to extend the duration and protection may be required.This study aims to investigate the safety, tolerability, and immunogenicity of the VLA2001 vaccine as a booster dose to adults 18 years and older who were primed with another licensed inactivated COVID-19 vaccine at least 6 months prior to enrollment.