Prospects for Takeda’s dengue vaccine just turned brighter following fresh data from the company’s Phase II trial. For Takeda, the data is likely welcome considering the company already has a massive pivotal trial underway for the vaccine. For competitor Sanofi … perhaps not so welcome.

The data show Takeda’s vaccine, called TAK-003, fortified the immune systems of patients for 18 months by boosting antibodies that fight the virus. The vaccine was also well-tolerated. For the trial, Takeda is testing 1,794 children and adolescents living in regions prone to dengue outbreak.

The update is good news for the company’s ongoing Phase III trial, which is testing the vaccine in 20,000 kids in Latin America and Asia. The randomized population is receiving two doses of either the vaccine or a placebo on day 1 and day 90. The Phase II study indicated a two-dose regimen (with the booster given at 90 days) was the right choice.

Takeda has already completed nine Phase I and Phase II trials for this vaccine, capturing evidence of safety and efficacy. Initial results from the Phase III study will start to roll in next year. Takeda is already getting ready for commercial roll out. The company has invested more than €100 million in a new vaccine plant to manufacture a global supply.

“The reduced incidence of dengue in children and adolescents receiving TAK-003 is encouraging, however data from our ongoing Phase 3 efficacy trial, TIDES, are required to confirm these findings,” said Derek Wallace, the lead at Takeda’s dengue program, in a statement.

Sanofi will be watching closely. The pharma giant spent more than $1.5 billion over two decades to develop Dengvaxia, the first approved vaccine for dengue. But the drug’s initial sales were a bit of a disappointment last year. Still, analysts have estimated the market for this drug could break a billion dollars a year.

Unless Takeda takes a big slice of the pie. Last summer, when Takeda set out to restructure its global R&D operations, CEO Christophe Weber made a commitment to vaccines. Other than TAK-003, the company is pursuing BARDA-funded studies on a Zika vaccine as well as a polio effort backed by the Bill & Melinda Gates Foundation.