mRNA based vaccines have contributed significantly to the fight against COVID-19.  Two mRNA vaccines have already helped bring the pandemic under control in many parts of the world. The global attention and willpower to bring new technology platforms to market has revolutionized the vaccine and public health landscape for the foreseeable future.

In this context, we recently announced positive phase 1/2 study interim results for our mRNA-based COVID-19 candidate vaccine. Taking into account public health needs and given sufficient mRNA COVID-19 vaccines supply can be expected going forward, we have decided not to pursue the development of our COVID-19 mRNA candidate into a phase 3 clinical study.

Building on these positive results, we will focus our mRNA resources in our newly created mRNA Center of Excellence to address future pandemics and other infectious diseases and therapeutics where there is a strong unmet need.

“Our mRNA vaccines Center of Excellence aims to lead the field in this next chapter of vaccine innovation,” said Jean-Francois Toussaint, Global Head of Research and Development at Sanofi Pasteur. “During the COVID-19 pandemic, mRNA technologies demonstrated potential to deliver new vaccines faster than ever before. However, key areas of innovation such as thermostability and tolerability improvements will be critical to unlocking the applications of mRNA in routine vaccination against a broader set of infectious diseases and across all ages.”

We plan to have a quadrivalent influenza mRNA-based vaccine candidate in clinical trials in 2022.

How mRNA vaccines are made

Rather than producing spike proteins in the lab, messenger RNA (mRNA) vaccines are designed to produce the desired antigens using the body's own protein-making machinery.  Messenger RNA vaccines deliver instructions directly to a person's cells. When the cell carries out those instructions, they make just enough spike protein to stimulate the immune system to launch a fleet of antibodies to help fight it.

Here's how it works:

Discover how an mRNA vaccine is designed to work

Our approach to innovation in mRNA Vaccines

Since 2018, we have been working with Translate Bio, a clinical-stage biotechnology company that specializes in messenger RNA (mRNA) therapies, to design and develop an mRNA technology platform for vaccines.

Updates on our COVID-19 Vaccines

Updates on our COVID-19 Vaccines

The Adjuvanted Recombinant Protein-based Vaccine Candidate


  1. Xu S, Yang K, Li R, Zhang L. mRNA Vaccine Era-Mechanisms, Drug Platform and Clinical Prospection. International Journal of Molecular Sciences. 2020 Sep;21(18). DOI: 10.3390/ijms21186582