NEW YORK (Reuters) – The race to find protection against the Zika virus is fueled by something often missing from tropical disease research: the potential for big profit.

The prospect of a blockbuster vaccine against a mosquito-borne virus has accelerated the pace of development and attracted the interest of big drugmakers, including Sanofi SA, GlaxoSmithKline Plc and Takeda Pharmaceuticals.

Although Zika infections are mild or asymptomatic in most people, demand for a vaccine is expected to be strong because it can cause devastating birth defects, pharmaceutical executives and disease experts said.

The most lucrative market is seen in travelers seeking inoculation against the virus that has moved rapidly across the Americas and is the only mosquito-borne disease also spread through sex.

“It scares people,” said Scott Weaver, a virologist with the University of Texas and chairman of the Zika task force for the Global Virus Network. “Europeans and Americans can pay a pretty high price for these kinds of vaccines.”

A vaccine could come to market in as little as two years. Even if the current outbreaks in Latin America and the Caribbean burn out by that time, people living in those regions are expected to want protection against a return of Zika.

Tens of millions of travelers from United States and other wealthy nations, including people on business trips with corporate-sponsored health coverage, are expected to get vaccines before visiting areas where Zika is circulating.

“If you consider just a portion of the U.S. traveler population, we can conservatively envision a Zika market opportunity exceeding $1 billion” a year, said Joseph Kim, chief executive of Inovio Pharmaceuticals, a Pennsylvania company that is farthest along in the development path with human testing of a vaccine candidate underway in hard hit Puerto Rico.

Drugmakers and disease experts also envision the vaccine becoming standard care for girls before puberty to guard against birth defects in future pregnancies. Boys also could be candidates to protect eventual sexual partners.

“Hopefully a vaccine can be developed that’s sold for a low cost in endemic areas,” Weaver said.

ZIKA’S DIFFERENCE

Blockbuster sales for vaccines against mosquito-borne viruses are unheard of. Sanofi’s dengue vaccine, approved in 11 countries, is generating near-blockbuster expectations, the biggest in the market by far. Analysts forecast annual sales for Dengvaxia reaching about $900 million by 2020, according to Thomson Reuters data.

Efforts to find a malaria vaccine are purely philanthropic. The Bill and Melinda Gates Foundation has contributed significantly to GSK’s decades-long effort to produce a vaccine for children in Africa. Development is ongoing, and GSK expects no profit.