Frequently Asked Questions

Last update: May 27, 2021

Why is Sanofi pursuing two COVID-19 programs?

We are pursuing two different vaccine candidates in parallel to increase chances of success and maximize production capacities to help meet worldwide demand.

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  • We are doing so in unique partnerships with industry peers, including GSK (for the recombinant protein vaccine) and Translate Bio (for the mRNA vaccine).
  • One of our vaccine candidates is developed with well-established, recombinant-protein technology already used effectively in influenza vaccines.
  • The fact that this vaccine technology is well established also means the distribution channels and methods are already in place to help ensure global availability of high-volume supply.
  • We have a massive vaccine manufacturing and pharmaceutical industrial footprint, which will support our own vaccines’ supply as well as support supply of other companies' vaccines while we complete our clinical development programs.

How can Sanofi assess safety with accelerated development timelines?

Monitoring and evaluating the safety of any investigational vaccine is of utmost priority. The development of a vaccine candidate will continue only if its risk/benefit profile remains acceptable, as with any new vaccine. 

In the development of COVID-19 vaccines, safety controls are no different from what we normally do for any new vaccine candidate. We are working with regulatory authorities to ensure all required safety data are collected and an Independent Data and Monitoring Committee will be integrated in our development programs. Sanofi Pasteur is accelerating the process in other areas, for example some clinical trial phases overlap one another to shorten the total development time. Regulatory authorities are also helping by reviewing data in real time throughout clinical trials and prioritizing new COVID-19 vaccine reviews. We are carrying out full safety monitoring that occurs in all our clinical trials, which includes rigorous and objective scientific review of safety and efficacy data prior to any regulatory agency’s approval of our COVID-19 vaccines.

Why aren’t Sanofi COVID-19 vaccines first to market? 

For us it’s never been about a race to be first. Ending a pandemic requires a global collaborative effort, and the more approaches and partnerships that move forward the more we will increase our chances of success. 

We continue to rapidly respond to the evolving challenge of COVID-19, and we are exploring all vaccine options as part of these efforts, including pursuing two different technological approaches to help increase odds of success. We are following the science in the pursuit of our vaccine candidates with multiple partners, and on the timelines required by each initiative to give us the best chance of bringing COVID-19 vaccines to people worldwide.

What does it mean for a vaccine to be less than 100% effective?

Efficacy rates are estimates scientists make when observing clinical trials. In those trials, they compare the number of people in a group of vaccinated participants who may still become infected with COVID-19, with the number of people in a control group who have received a placebo and who still become infected with COVID-19. The efficacy percentage indicates the likelihood the vaccine will protect a person from infection based on the outcome of participants’ infection rates in each group, vaccine and placebo, over a given amount of time (~ 1 month after second dose for COVID-19 vaccines). The World Health Organization (WHO) has established a target product profile for COVID-19 vaccines, including optimal efficacy levels at less than 100% (and a minimum of 50%). Even with vaccines that achieve less than 100% efficacy in clinical trials, a significant reduction of hospitalizations and severe cases are averted.

How will Sanofi’s vaccines be allocated to people around the world?

We will work with our partners, GSK and Translate Bio, governments and NGOs to ensure our COVID-19 vaccine(s), if and when approved, will be available worldwide. Financial systems such as Advance Purchase Agreements and the COVAX Facility have been established to help support broad vaccine supply.   

The COVAX Facility is the international public health community's pooled procurement mechanism (led by the WHO, Gavi and others). COVAX helps participating countries gain access to vaccines in an efficient and optimally equitable way. We are participating in this Facility and will continue discussions with WHO, Gavi and partners as the pandemic and our vaccine's development evolve.

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How does Sanofi plan to manufacture so many doses of COVID-19 vaccines without disrupting regular business?

Our COVID-19 activities are in addition to our pre-existing activities and we continue to receive new market authorizations for several new treatments and vaccines as well as meet our product supply commitments around the world despite the pandemic context. Sanofi benefits from a large global R&D and industrial footprint that we are extending across our manufacturing sites in the US and in Europe to support COVID-19 vaccine projects.

What will your clinical trials show for the recombinant protein adjuvanted vaccine candidate?

We have announced initial results of the phase 2 study of our adjuvanted recombinant protein COVID-19 vaccine candidate and the start of a pivotal phase 3 trial. The candidate has so far demonstrated strong immune responses across all adult age groups. In parallel, Sanofi and GSK intend to conduct booster studies in order to assess the ability of a lower dose of the vaccine to generate a strong immune boost regardless of the initial vaccine platform received.

Sanofi routinely publishes key protocol details on clinical trial registries such as and full protocols and statistical plans are also shared at the time of publication of study results at the latest.

Read more on our phase 2 trial and results here.

Where are Sanofi’s clinical trials being held and where can I learn more?

For the adjuvanted recombinant protein vaccine candidate, the phase 2 study was held in the United States and Honduras. Phase 3 will evaluate safety and efficacy of the vaccine candidate in a large-scale study including more than 35,000 participants across several countries, including sites in the US, Asia, Africa, and Latin America.  Selection of study sites is made based on several criteria including available epidemiological data on COVID-19 circulation and availability of research sites.

For the vaccine using mRNA technology, we announced the start of phase 1/2 clinical trials on March 12.

Are you able to manufacture COVID-19 vaccines of other companies?

It is our responsibility towards public health to contribute to solving the COVID-19 pandemic in every way possible. While our utmost priority remains to advance our two COVID-19 programs, we have offered our temporarily available capacities to support manufacturing and supply of BioNTech’s approved COVID-19 vaccine which is co-developed with Pfizer, the vaccine developed by Johnson and Johnson and the vaccine developed by Moderna. We are planning to start producing and delivering doses from summer 2021 onward.

When will Sanofi’s vaccines be available? 

We are following the science in the development of our two vaccine projects. Concerning the recombinant protein vaccine, a global phase 3 study began on May 27. Positive results from phase 3 would lead to regulatory submissions in the second half of 2021, with the vaccine’s potential availability in Q4 2021. Our other vaccine using mRNA technology entered into phase 1/2 clinical trials on March 12.