Sanofi (SNY 0.52%) has a new COVID-19 vaccine candidate ready to start clinical trials in humans. On Thursday, it reported that MRT5500, which was discovered by Translate Bio (TBIO), induced antibodies to the coronavirus in mice and nonhuman primates. The vaccine also induced a T cell response.

MRT5500 is a messenger RNA (mRNA) vaccine candidate, similar to the candidates being developed by Moderna and the Pfizer/BioNTech collaboration. Using mRNA in vaccines is a new technology and as yet, no mRNA vaccines for any conditions have been approved by the FDA.

Blue gloved hand holding bottle of COVID-19 vaccine

Image source: Getty Images

Other mRNA vaccine candidates for COVID-19 came out of their initial development stages quickly. Moderna was able to start a phase 1 trial for its vaccine candidate on March 16. Pfizer and BioNTech got their coronavirus candidate into human trials on April 29. Both are now in phase 3 trials. 

The process for Sanofi and Translate Bio has been slower. In March, the companies expanded their existing partnership to include finding a COVID-19 mRNA vaccine candidate. In June, Sanofi gave Translate Bio $425 million to expand that partnership yet again. Now, their vaccine is finally ready to start human trials.

Concurrently, Sanofi pursued another COVID-19 vaccine candidate in collaboration with Glaxo. That one is a "classic" vaccine, similar to the candidate being tested by Novavax. It's a recombinant protein vaccine, delivered in combination with an adjuvant designed to induce a stronger immune response. It's currently in phase 1/2 trials.

So while Sanofi is trailing in the race to bring a COVID-19 vaccine to market, it now has two different candidates that could eventually cross the finish line. The stock was down by 2.6% in mid-afternoon trading Thursday.