More than 30 years have passed since Dr Sutee Yoksan began his painstaking work into developing a vaccine against Dengue fever, a mosquito-borne disease that is now affecting more people than ever before.
The top researcher and director of the Centre for Vaccine Development at Mahidol University, Sutee, then a doctoral degree student, started work on the vaccine in 1980 at the invitation of Dr Nat Pamornprawat, Mahidol University’s rector at that time.
“Thailand is the pioneer in dengue vaccine research and development. It was initiated by Dr Nat, who wanted to use our scientific knowledge to benefit vaccine research in developing countries. That was a very new idea at the time,” Sutee says.
“Dr Nat suggested we should develop a vaccine that could prevent all four types of dengue in just one dose. That meant researching each type of vaccine and combining them into one universal immunisation. He did not allow us to bypass any process, so our study was long and arduous but also very worthwhile.”
Sutee explains that the team started by raising the virus in a primary dog kidney cell and then generating a weaker virus that would be unable to cause illness but would instead teach our antibodies how to deal with dengue virus.
In 1984, after four years of research, the prototype of the first set of dengue vaccine was completed and the World Health Organisation (WHO) was invited to inspect and review the vaccine prior to testing on humans. Clinical trials commenced a few years later and ran through 1993.
“We tested the vaccine on 500 Thai volunteers and also 20 American citizens, as the vaccine passed the United States’ Food and Drug Administration standards for testing in the USA,” Sutee says.
But the vaccine had problems. “It was found to be only 75-per-cent effective in preventing all four types of dengue infection. The patent for this vaccine was then granted to Pasteur Merieux Serums & Vaccins, as the predecessor of Sanofi Pasteur was known,” Sutee explains.
“During the 1990s we also let the US Centres for Disease Control and Prevention use our prototype to continue vaccine development using genetic engineering methods, as we were still uncertain which vaccine development method, cell culture or genetic engineering, was best,” he says.
“On our side, we worked on second and third sets of vaccines from 2004 using the cell culture technique and completed that in 2009. It was then that we were forced to face up to the fact that Thailand did not have the advanced technology required to produce the vaccine,”
The path towards success was never going to be been easy given the obstructions that bar Thailand from being able to produce a dengue vaccine using its own technology.
“The main problem is that the Government Pharmaceutical Organisation (GPO) does not have either the technology or qualifications to produce our vaccine. We have been trying to ask them to reform, but until now we’ve been unsuccessful,” he says.
Another obstruction, Sutee says, is the lack of personnel involved in the vaccine research and production field. “Despite the thousands of new pharmaceutical graduates every year, almost none of them want to work in the vaccine research.
“I’ve said several times that I am happy to train new researchers through learning by doing, but unfortunately no agency has accepted my offer,” he says.
“The upper level of decision-makers are very short-sighted on this issue. They don’t see vaccine research as a priority. We’ve thus had to grant the vaccine patent to Japanese firm, Chemo-Sero Therapeutic Research Institute (Kaketsuken), and to the Serum Institute of India for the mass production of our vaccine,” he says.
Mahidol University granted the vaccine patent to Kaketsuken in 2011 and to Serum Institute of India in 2013. “Our main objective for giving the patent to these two companies is to allow the vaccine to be produced at lower prices,” he explains.
“Both companies are now working on the vaccine testing process and by 2020 we will see the first mass production of our vaccine.I personally feel that an important vaccine like the one for dengue must be cheap so it is accessible to the poor, often the ones who need it the most.”
Now 66, Sutee, who earned his PhD in Pathobiology from Mahidol University in 1989 and also conducted post-doctoral dissertations in immunology with the University of Hawaii and Oxford University, is still working to develop the perfect dengue vaccine.
“We’re also researching vaccines for Japanese encephalitis, Chikungunya fever and Zika fever,” he says.
“Even though I’m past retirement age, I want to carry on working. Developing vaccines requires a long period of time to complete and I am determined to make this world safer from infectious diseases through vaccination technology,” he says.