Thailand has come a long way since Dec 1, 1988, was dedicated as Aids awareness day. Last year, there were close to 500,000 HIV cases in the country, while UNAids reported approximately 37.6 million HIV cases globally.
Currently, numerous methods exist to protect against infection such as using a condom; taking medication in a preventive manner; proper treatment of individuals with HIV using antiretroviral medication to keep viral count low to stop spread; and using treatment as prevention (TasP) which refers to HIV medication to prevent sexual transmission.
However, these options are only successful in preventing infection if properly implemented in a timely fashion.
On the other hand, vaccines have proven to be real game-changers as just a few doses allow for prevention over a longer period while combating antiviral resistance and spread of Aids.
Veteran researcher Prof Punnee Pitisuttithum, head of the Department of Clinical Tropical Medicine, Vaccine Trial Center, Faculty of Tropical Medicine, Mahidol University, said that a safe, effective HIV vaccine is one of the most pivotal prevention tools to ending the epidemic.
Thailand has been conducting research into an HIV vaccine since 1993. Most recently, it collaborated with the US Military HIV Research Program; US National Institutes of Health; Thailand Ministry of Public Health; USAMD-AFRIMS Vaccine Trial Centre; and Mahidol University. They engaged in advancing concepts for the next generation of vaccines and evaluating novel strategies involving rapid dose administration, late boosting, and fractional dosing.
"The RV144 'Thai Study' which came out of this collaboration was the first clinical trial to show modest efficacy in reducing HIV risk by using an ALVAC HIV vector-based vaccine, followed by the AIDSVAX (rgp120 subtypes B/E) as a protein boost vaccine. Over the past decade, the trial has provided scientific knowledge to help guide the next generation of vaccine research and development," said Punnee.
"The subsequent RV305 study examined the effect of late boosting the original RV144 regimen. Healthy participants from the original RV144 trial received a vaccination six to eight years after RV144, and a sub-study evaluated an additional boost given nine to 12 years post RV144. Results showed that boosted participants had stronger immune responses than the peak immune response in RV144, indicating the original RV144 series laid down long-term immune memory. The RV306 study assessed the effect of an additional vaccine boost to the RV144 regimen at varying intervals between the priming vaccine series and the boost. Healthy volunteers received the RV144 regimen, followed by an additional boost at months 12, 15 or 18. The results showed that longer intervals between the primary vaccination series and late boost improved immune response."
Punnee added that the army-developed Army Liposome Formula (ALFQ) also provides insight into the role of adjuvants in priming versus boosting administered to approximately 120 healthy participants from the RV306 study. A future study will also look into the potential use of fractional dosing of a candidate HIV vaccine to determine whether smaller doses of valuable antigen can induce an effective immune response so that the vaccine can be made available to a wider segment.
Punnee said that the current project, which is scheduled for launch next year, will be based on a similar vaccine concept that the Thai government used for Covid-19; a single dose or two doses of Sinovac or Sinopharm, followed by either AstraZeneca or Pfizer. This is called a heterologous regimen.
"HIV vaccine research provided a platform for Covid-19 vaccine development, which is why scientists managed to create the Covid vaccine so quickly as it was based on a platform already available under R&D by other infectious diseases, especially HIV vaccines, which remain a ways off before they can be used for prevention. The reason for this is because the HIV virus infects host immune cells, so it is difficult to treat compared to other viruses."
Punnee said that on World Aids day, her hope is to get an HIV vaccine soon because a direction has now been provided by Covid-19 vaccines along with lessons learned from them and from HIV vaccine R&D.
"In the hopes of better protection, we are looking forward to achieving a platform that will work and can be used as a campaign in the future. Hopefully, the regimen we are currently working on will help to stimulate a better immune response. I think it is very important that HIV vaccines remain an important tool to control HIV transmission."
Punnee said new HIV cases come from high-risk populations, which includes men having sex with men (MSM), transgenders and drug users. Of new HIV infections in Thailand, 41% of people newly infected are MSM.
Thanks to HIV/Aids campaigns over the years, HIV cases are now mostly restricted to high-risk groups.
On when to expect vaccines for HIV, Punnee said: "As I mentioned, we have started a new combination regimen based on lessons we learned from Covid-19 vaccines, so the development is going to be quicker than in the past. With the new technology and overall knowledge we have gathered from Covid, there is hope that we can expedite the process to achieve results in the next five to 10 years."
Interestingly enough, she noted that the rapid development of Covid-19 vaccines has helped expedite the progress of other vaccines such as HIV. Comprehensive strategies will therefore help Thailand accomplish the World Health Organization's goal to end the Aids epidemic by 2030.
The researcher said that while the number of HIV cases remains low, what the country needs is to achieve zero stigmatisation of HIV-positive patients.
"The government has worked hard to discourage the public from stigmatising HIV-positive people by educating communities against this practice. However, there are some people that continue to stigmatise HIV patients," Punnee said.
"Besides educating the public against the stigmatisation of HIV-positive patients, the government has also encouraged high-risk groups to get themselves tested and offers them antiretroviral drugs under treatment as prevention."
To take the research and development of HIV vaccines to the next level in Thailand, Punnee said that besides funding, there needs to be support from government policies, communities, and research networks as this is a collective effort.
