Nicholas Jackson, who heads up the effort, said on Thursday he had now assembled a team of more than 80 in-house experts who would start preclinical tests of a potential vaccine in animals this spring.

The first studies in humans are likely next year, subject to fast-track clearance from regulators, whose cooperation will be central in achieving the goal of shaving years off the typical decade-long process of vaccine development.

Sanofi is chasing rivals such as India’s Bharat Biotech, U.S. firm Inovio and the U.S. National Institutes of Health, which have all also started Zika vaccine work.

But it has unique capabilities as a major vaccine producer and the first company in the world to launch a shot for dengue, a related mosquito-borne disease. It already sells similar established vaccines for Japanese encephalitis and yellow fever.

Jackson aims to piggy-back on the technology in these products for Zika, which should speed up development and offer reassurance on safety, since the basic vaccine “backbone” has already be used without a problem in millions of patients.

The French group’s Sanofi Pasteur vaccine unit also has a big factory in Lyon capable of producing 100 million doses a year of its four-strain dengue shot, which could be adapted if needed to make even more doses of a single-strain Zika product.

“It is our ambition to slash years off the normal timeline required for a vaccine,” Jackson told Reuters.

“Preclinical animal studies will start imminently and we will go through the various stages of research and development that will allow us to potentially enter the clinic next year.”

In total, the World Health Organization estimates at least 15 companies and academic groups are researching vaccines against Zika, which has been linked to birth defects and a rare neurological illness in Brazil and other parts of Latin America.

It is not yet proven that Zika actually causes microcephaly, or abnormally small heads, in babies or Guillain-Barre syndrome(GBS) in adults, but evidence of a connection is growing.

Jackson said Sanofi was eager to collaborate with other groups, since it was important to try different vaccine approaches, and Sanofi itself plans to test a number of candidates.

“We may end up with several vaccines that work very well and we are blessed with a choice,” he said.

DIFFERENT AGE GROUPS

On paper, developing a Zika vaccine should be easier than for some diseases, since the genetic code of the virus is more than 95 percent the same across samples, in contrast to the huge variability seen, for example, in HIV.

“Because the Zika virus seems to be well-conserved at the genetic level that greatly improves the chances of success in developing a vaccine,” Jackson said.

Designing clinical trials, however, could be a complicated matter, since pregnant women are often excluded from such tests until the safety of new drugs or vaccines is well-established in other population groups.

One option could be to vaccinate girls before they are sexually active, as happens with HPV immunization, although the benefits of this approach would take time to become evident. At the same time, there may also be a case to protect the broader population against GBS.

“We need to think about a Zika vaccine that is potentially going to be given to different age groups,” Jackson said.