Krishna Ella never expected to be holding the key to fighting a new global health emergency. Yet, his Indian firm, Bharat Biotech, has become the first in the world to have two vaccine candidates against the rapidly spreading Zika virus, which has infected millions of people in Latin America and has the potential to spread worldwide.

Zika doesn’t cause much harm to adults. Most infected individuals are symptomless, and those who experience a bout of fever or red rash often recover within a few days. What has raised alarm is its link to the serious neurological birth defects known as microcephaly, in which babies are born with tiny brains.

Bharat Biotech got the jump on every pharmaceutical company in the world when it started working on a Zika vaccine in November, 2014. The current Zika outbreak is thought to have begun in Brazil in April, 2015.

“We never expected that the virus will become a serious issue,” Ella told Quartz. The virus drew the Hyderabad-based firm’s attention because the clinical features of early-stage of Zika infection are indistinguishable from those of dengue and chikungunya, two mosquito-borne infections that are prevalent in India.

There is now a rush to develop a vaccine. Global firms including France’s Sanofi and Japan’s Takeda have begun their own research. But Bharat Biotech was the first company to file a patent for a Zika vaccine, which is now in pre-clinical testing as the firm prepares to test it on animals.

“We were the first ones to secure the chikungunya genome in 2007. Still, there is a perception that an Indian company cannot do path-breaking research,” Ella, who has a PhD in biochemistry from the University of Wisconsin-Madison, told Quartz. He founded Bharat Biotech in 1997 after he returned to India from the US.

Two ways to prevent Zika

Vaccines work by stimulating a patient’s immune system with a weaker version of the disease, preparing the body to defend attacks by the real contagion. Bharat Biotech’s has two vaccine candidates.

The first uses strands of DNA that belong to the Zika virus. While these so-called recombinant DNA vaccines are easier to create, they don’t always produce a strong enough immune response.

The second is an inactivated version of the Zika virus, which means the virus is unable to replicate and cause infection, but it is still able to trigger an immune response. Experts believe that this type of vaccine stands a better chance of success.

It is not clear if and when Bharat’s vaccines will reach the market. Animal testing is expected to take about five months, and then they would need to be tested on humans. The vaccine doesn’t just need to be effective in trials; Indian regulatory authorities also need to expedite the process, Ella said. Passing through those stages could take many years, but Ella is confident that, once approved, Bharat Biotech can produce millions of doses within months.

Zika is transmitted by the bite of an infected Aedes mosquito, which is rampant in India. The country reported nearly 100,000 cases of dengue in 2015 and some 13,000 cases of chikungunya in 2014; both of which are transmitted by the same mosquito species. Malaria takes a even bigger toll in India, with some one million cases, but it is spread by a different species of mosquito.

In Latin America, Zika’s spread is restricted to the regions where Aedes mosquito is widely found. In rare cases, however, the disease could spread through sexual transmission. On Feb. 2, the US reported first such case in the current outbreak.

The vaccine business model

Vaccines are a tough market for pharmaceutical companies: success rates are low and costs are high. Then, in most cases, once the vaccine is ready, there is not much money to be made in sales. The dose, after all, is supposed to stop individuals from getting a disease, rather than provide continuous treatment.

However, the one thing in Bharat Biotech’s favour is that it has been working on neglected tropical diseases. As the name suggests, these diseases have received little attention and thus are rich areas to pick low-hanging fruits.

The privately held firm generates annual revenue of around $100 million. It holds 50 patents and has delivered more than three billion vaccine doses in more than 65 countries.

Bharat Biotech has in the past received monetary aid for research and development from philanthropies, such as the Gates Foundation, and governments of India, Norway and the UK. In March 2015, Bharat Biotech launched the Rotavac vaccine (pdf), which is used to treat rotavirus diarrhoea.

In the pharma industry, India-made drugs have often been criticized by regulatory agencies like the US Food and Drug Administration for quality control . But Ella insisted that if Bharat Biotech’s Zika vaccines succeed in trials, its manufacturing will be compliant with all international standards.