World AIDS Day: Where do we stand on HIV-AIDS?

Our country has the third highest number of estimated people living with HIV in the world. The estimated number of people living with HIV/AIDS in India was 2.08 million (20.9 lakhs in 2011) out of which an enormous 86% of whom were in 15-49 years age group.

Children less than 15 years of age accounted for 7% (1.45 lakh) of all infections in 2011. Of all HIV infections, 39% (8.16 lakh) were among women.

"The HIV epidemic in India is concentrated, with high prevalence among high-risk groups (i.e., Intravenous drug users, sex workers, men who have sex with men and transgender people), moderate prevalence among bridge populations (i.e., people, who, through close proximity to high risk groups are at the risk of contracting HIV. Quite often they are clients or partners of male and female sex workers. Truckers and migrant labours are major bridge populations), and low prevalence among general population," says Dr Satish Chandra, Advisor to Credihealth.

Three primary routes of HIV transmission in India: (i) unprotected sex (ii) injecting drug use (iii) unprotected anal sex between men.

Why is an AIDS Vaccine important?

Vaccines are powerful public health tool and have proven to be the world's most effective and cost effective preventive mechanism.

- A 70% effective AIDS vaccine could reduce new infections by 40% in its first 10 years; and 50% in its first 25 years.

- Globally, about 36.9 million people reported to be living with AIDS, in the year 2014. (Source: UNAIDS)

- AIDS is the #1 killer of women of reproductive age, globally

- AIDS is the #2 killer of adolescents, globally

How is India positioned as part of global efforts to discover a vaccine?

- India's strength lies in its rich pool of scientists and healthcare professionals who are globally competitive, a competitive scientific infrastructure and a thriving bio pharma industry. Additionally, the Government of India is committed to this critically important cause.

Why is the making of a vaccine so challenging?

- HIV is a complex pathogen

- Part of what makes HIV such a difficult virus to combat is its ability to furiously mutate the trimeric envelope protein on its outer surface. This high mutation rate gives rise to numerous HIV subtypes that circulate around the globe, letting the virus to escape the responses that human immune systems mount against it.

- That the virus could mutate and regain its pathogenicity has rendered approaches like using attenuated versions of the pathogens to immunize people or using a killed or inactivated virus adopted for making other vaccines like measles, polio and influenza, unsuccessful thus far. Scientists are learning to be as wily as the virus to discover new ways to combat it.

- There are other challenges unique to HIV. After following the transmission, virus disseminates and establishes a persistent infection, including hidden reservoirs from which it can strike again at any time. The opportunity for a vaccine-induced response to avoid infection or to control the initial, limited infection is thus short-lived.

- Scientists still don't understand how to elicit specific, durable, and protective immune responses against HIV.

Where are we today on the road to a viable AIDS Vaccine for humans?

- Progress during the past five years is spurring creative and promising new approaches. Scientists have analyzed potent antibodies that neutralize a broad spectrum of HIV variants circulating around the world.

- In addition, several preclinical studies of novel vectors for HIV vaccine have produced promising results, far exceeding the performance in similar studies of candidates that are today in clinical trials.

- Breakthrough discoveries are leading to more refined and targeted vaccine designs

- Some scientists are making significant progress by employing reverse-engineering or structure-assisted vaccine discovery. In this approach, neutralizing antibodies from chronically infected HIV patients is isolated broadly whose immune systems produce them.

- Even the clinical trials with disappointing results are and will continue to be important. The lessons learned in HIV vaccine research are also helping to fight flu, malaria, cancer, Ebola.

- Another major advance has been the scientists' ability to obtain an atomic-level image of the HIV envelope trimer, the principal target for broadly neutralizing antibodies.

- Collectively, these efforts are paving the way for a non-traditional immunoprophylaxis that can protect against HIV infection without depending on the lengthy and complex antibody maturation process required to generate broadly neutralizing antibodies through immunization. 

-ANI