With antiretroviral therapy, HIV vaccine has become a chronic but manageable disease. Still, there are challenges that need to be tackled to eliminate AIDS by 2030, warns Dr Ishwar Gilada, President, AIDS Society of India. Considering India diagnosed its first case in 1986 and there’s enough scientific evidence to adopt ways to prevent HIV transmission and care for people living with HIV (PLHIV), the knowledge acquired is still not being actualised on the ground. What are the obstacles?
Current status of the HIV vaccine disease burden in India
There are approximate 2.3 million people living with HIV (PLHIV) in India. Of these, 76% know their HIV status. Of those aware of their status, 84% are on antiretroviral treatment (ART). Among those on ART, the virus has been suppressed in 84% of cases. New HIV infections in India have declined by 37% between 2010 and 2019 compared to the global average of 23%. Similarly, during the same period, AIDS-related deaths have declined in India by almost 66% against the global average of 39%, according to the NACO report of 2020. The decline is higher in states like Andhra Pradesh, Maharashtra, Karnataka, Telangana, Tamil Nadu and West Bengal and noticeably among women and children at 73.7% and 65.3% respectively.
HIV vaccine burden higher in Mizoram, Nagaland and Manipur
Despite commendable progress, challenges continue to confront our goal to end AIDS by 2030. Mizoram (2.32%), Nagaland (1.45%), and Manipur (1.18%) had a higher than 1% HIV prevalence in the adult population in 2019. HIV prevalence in injection-prone drug users is almost 28 times higher than overall adult prevalence. Similarly, HIV prevalence among transgender people, LGBTQ and female sex workers is six to 13 times higher than adult prevalence. Among inmates in central jails, where the population with high-risk behaviour is over-represented, HIV prevalence is nine times higher than the adult prevalence. More than 69,000 people were newly infected with HIV in 2019, twice the number envisaged by NACO, 2020 (75% reduction since 2010).
The newer generation of candidate vaccines with better ability to induce an immune response against HIV
Currently, all are candidate vaccines because there is no finished product which has been commercialised or licensed for human usage. The first candidate vaccine was made in 1987 by Dr Jonas Salk and went into phase I trial in 1989. With Dr Salk’s track record, who had invented the polio vaccine, we were all very hopeful but that failed.
Broadly, here are two types of vaccines: One for those who are HIV negative, termed a preventive vaccine or immunoprophylaxis. The other one is for PLHIV, to prevent disease progression to clinical stages and that is called a therapeutic vaccine or immunotherapy, akin to treatment. There has been a lot of progress in this area after the success of long-acting antiretrovirals, Cabotegravir and Rilpivirine, where the PLHIV needs to be treated with a monthly or bimonthly injectable rather than daily oral medicines.
Several studies are on broadly neutralising antibodies (BNA) for both types of vaccines. In prophylactic HIV vaccines, a total of some 95 candidates were assessed, of which more than 30 HIV candidate vaccines have been tested in approximately 60 Phase I/II trials, involving more than 10,000 healthy volunteers. Most of the initial trials were conducted in the USA and Europe, but several have also been conducted in developing countries like Brazil, South Africa, China, Cuba, Haiti, Kenya, Peru, Thailand, Trinidad, and Uganda. The results have confirmed the safety of the vaccines and have provided important scientific information to develop newer generations of candidate vaccines with better ability to induce immunogenicity or anti-HIV specific immune responses.
After Covid vaccines, two specific platforms that can be used for HIV
After the COVID vaccine success story, there are two specific COVID vaccine platforms, which can be used for HIV – an mRNA and DNA one. Broadly neutralising antibodies (BNAbs) are produced by certain types of B immunity cells, which are rare. Maybe only one in 300,000 B cells has this capability. The mRNA vaccine aims to stimulate the production of bnAbs that can act against many variants of HIV. So, the mRNA vaccine will instigate B-cells and try to produce more neutralising antibodies.
Challenges with HIV vaccines
Vaccine research and development is a long-drawn and very expensive proposition. With no commercial vaccine in 35 years, there are very few companies and research laboratories which would invest in vaccine development. Moreover, with a very high success rate of ART in India, HIV vaccine development has taken a back seat. Even if candidate vaccines against HIV are found successful in phase 2 and can be taken forward to phase 3 of trials, the chances of getting emergency use authorisation or listing are less as HIV is no more an emergency.
This article is taken from Indian Express.