Sanofi looks for path forward with Dengvaxia as challenges mount

Sanofi's Dengvaxia is the subject of a controversy in the Philippines.

As questions swirl over who knew what and when in the Philippines regarding Sanofi's dengue vaccine, the company took a chance Wednesday to pause and explain its case. Despite challenges to using the vaccine following a new analysis, the drugmaker maintains its product can still play an important role in prevention efforts.

Sanofi execs said the drugmaker has not been asked to provide a refund of nearly $70 million for doses it sold the country after the Philippines stopped its vaccination campaign earlier this month. Further, they added, there's still a "targeted vaccination campaign" underway in Brazil despite the mounting controversy in the Philippines.

"We're aware of the press reports, but as of now there have been no specific demands made of Sanofi," a representative said on Wednesday's press call. "We are speaking with authorities, but that's all that we can say at this stage."

Last month, Sanofi reported that a new analysis found its Dengvaxia could cause more serious infections if given to those who haven't had a previous infection. The drugmaker sent the data to regulatory authorities and asked them to take the findings into consideration for a label change, taking a €100 million charge in the fourth quarter due to the development. Dengvaxia is already approved in 19 countries.

RELATED: Sanofi's Dengvaxia could do more harm than good in certain settings, study says

But the risk in dengue-naïve individuals hasn't exactly been a secret. Last year, a study published in Science by a team at Imperial College London highlighted the same issue with the vaccine.

Speaking with FiercePharma at the time, Sanofi Pasteur’s director of global medical affairs for dengue, Dr. Cesar Mascareñas, said the study didn’t change Sanofi’s expectations or strategies for the program because it was only a “mathematical model” and not “evidence-based.” Additionally, he said, it was one of eight models considered by the WHO in making its initial recommendation that the vaccine be used in countries where the virus is highly prevalent.

RELATED: Sanofi's Dengvaxia scrutiny mounts as Philippines slams brakes on dengue shots

Now, in the wake of the new analysis, WHO says it's taking another look at the vaccine and that it should only be used on people who are known to have had a prior infection.

That will likely pose a challenge, though. On Wednesday, Sanofi's global medical head for vaccines, Su-Peing Ng, told reporters that there's no widely available test for dengue, and that up to 75% of first infections can be silent. Those both represent major obstacles for a shot that can boost severe dengue risks if given to the wrong individuals.

Even still, in the Philippines, almost 9 in 10 people have had an infection by the time they reach an eligible age for the shot, Su-Peing Ng said, so the vaccine can still play a critical role in control efforts for a serious disease.

RELATED: Philippines plans legal action against Sanofi over Dengvaxia safety scare: official

Quickly after Sanofi sent its advisory last month, the Philippines canceled future vaccinations and struck up an investigation. In an interview with ABS-CBN news, the nation's top health official said he'd ask for a refund and that the government would end up suing the drugmaker. Sanofi responded that it was "surprised" by his comments and would continue to work with local authorities.

The episode highlights the risks vaccine research companies take on when they try to take on a disease like dengue. Aside from the product being a commercial letdown so far, Sanofi spent $1.5 billion and 20 years developing the vaccine that's been the source of a major controversy in its top market. It remains to be seen how many other countries will opt to purchase the shot while Takeda is working on a late stage vaccine of its own.