What is the mechanism of VLA-2001?

VLA-2001 is an inactivated virus vaccine designed to combat the SARS-CoV-2 virus, which is responsible for causing COVID-19. The development of VLA-2001 by Valneva SE, a specialty vaccine company, offers a promising addition to the global arsenal of COVID-19 vaccines. Understanding its mechanism provides insight into how this vaccine works to protect individuals from the virus.

At its core, VLA-2001 uses a traditional approach to vaccination by employing an inactivated form of the SARS-CoV-2 virus. The virus is grown in Vero cells—cells derived from the kidney of an African green monkey that are used widely in the production of vaccines. Once the virus has been cultivated, it is inactivated using chemical agents. This inactivation process ensures that the virus cannot replicate or cause disease, but preserves its structure so that the immune system can recognize it.

The inactivated virus in VLA-2001 retains the spike protein, a key antigen that the body uses to identify and combat SARS-CoV-2. When individuals are vaccinated with VLA-2001, their immune system encounters the inactivated virus and mounts an immune response. This response involves the production of neutralizing antibodies specifically targeting the spike protein. These antibodies are essential for preventing the virus from binding to and entering human cells, thereby thwarting infection.

In addition to neutralizing antibodies, VLA-2001 also stimulates the cellular immune response, particularly the activation of T-cells. T-cells play a crucial role in identifying and destroying infected cells, providing an additional layer of defense. The combination of antibody-mediated and cellular immune responses ensures a comprehensive immune defense against SARS-CoV-2.

The adjuvant used in VLA-2001 further enhances the immune response. An adjuvant is a substance that is added to a vaccine to boost the body’s immunological reaction to the target antigen. VLA-2001 uses an aluminum-based adjuvant, which has a long history of safe use in vaccines. This adjuvant works by stimulating the local immune cells at the site of injection, which helps to initiate and amplify the immune response to the inactivated virus.

Moreover, VLA-2001’s mechanism also involves multiple doses to ensure robust immunity. Typically, this vaccine is administered in a two-dose regimen, with the doses spaced several weeks apart. The first dose primes the immune system, while the second dose, or booster, significantly enhances the immune response, leading to higher levels of antibodies and a more prolonged period of protection.

In summary, the mechanism of VLA-2001 involves the use of an inactivated form of SARS-CoV-2 to stimulate an immune response. The vaccine introduces the inactivated virus to the body, which leads to the production of neutralizing antibodies and activation of T-cells. The inclusion of an aluminum-based adjuvant helps to amplify this response, ensuring strong and lasting immunity against COVID-19. Through this mechanism, VLA-2001 aims to provide effective and durable protection against SARS-CoV-2, contributing to the global effort to control the COVID-19 pandemic.