Cautious response to radical WHO model for HIV elimination

The five authors, writing in their personal capacity in The Lancet journal, said their mathematical model, using universal voluntary HIV testing and immediate treatment with antiretrovirals, showed a reduction in HIV incidence and drop in mortality to less than one case per   1 000 people per year by 2016, or within 10 years of full implementation of the strategy. They predicted that it would also reduce the prevalence of HIV to less than 1% within 50 years.

Their model is based on scientific evidence that a person newly infected with HIV is most infectious. When placed on ARV treatment soon after infection (even within multiple concurrent sexual relationships and without correct and consistent condom use) the chances of infecting their partners is reduced to almost zero.

 The use of ARVs for prevention is established in the prevention of mother-to-child programmes and through post-exposure prophylaxis for sexual assault and needle-stick injuries.

The Treatment Action Campaign (TAC) has cautiously welcomed the work as courageous and deserving of serious study by activists, governments, scientists and all health professionals. However, the activist group cautioned that the timing of this article during the World AIDS Day news-cycle may sensationalise and polarise a debate that requires utmost sensitivity and rigour.  

‘€œThere are many unanswered questions regarding the model’s proposed strategy for universal HIV testing and ARV treatment.  WHO and UNAIDS must now lead this discussion,’€ they said.

Latest figures reveal that roughly three million people worldwide were receiving antiretroviral therapy at the end of last year, but an estimated 6,7-million were still in need of treatment and a further 2,7-million became infected with HIV in 2007.

‘€œPrevention efforts might reduce HIV incidence, but are unlikely to eliminate this disease. We investigated a theoretical strategy of universal voluntary HIV testing and immediate treatment with antiretrovirals , and examined the conditions under which the HIV epidemic could be driven towards elimination,’€ the authors explained. They relied on data from South Africa and Malawi in designing the model.

They said their model showed that the strategy could also have additional public health benefits including reducing the incidence of tuberculosis and the transmission of HIV from mother to child.  

Indications are that up to now traditional prevention methods have failed to stem the epidemic. Despite substantial efforts to expand access to voluntary HIV testing, nearly 80% of HIV-infected adults in sub-Saharan Africa are unaware of their status and more than 90% do not know whether their partners are infected with HIV.

The researchers examined a strategy in which all adults in the test case communities accepted being tested for HIV once a year on average, and all HIV-infected people accessed antiretrovirals as soon as they were diagnosed HIV positive.

They also compared their strategy of immediately starting people diagnosed HIV positive on antiretrovirals to the current internationally accepted strategy in which antiretroviral therapy is started with a CD4 count of less than 350 in poor countries(In South Africa current guidelines dictate that patients are started once their CD4 counts dip below 200).

A costing exercise revealed that the staggering funding needed to implement the theoretical strategy for an epidemic of South African-type severity peaks in 2015 at $U3,4-billion per year. ‘€œAlthough the initial yearly cost of the theoretical strategy is higher than the present strategy it is well within UNAIDS projection,’€ the authors said.

They predicted that in the long term costs could reduce to very low amounts as progress towards elimination is achieved.

TAC identified some of the critical issues that must be raised when considering the implications of the model:

  • The mathematical modeling used in the study is extremely sensitive. Its parameters are liable to change drastically if values are altered. Therefore, it is essential that sensitivity testing be conducted in order to test the strength of the model’s findings.
  • Experts in the mathematical and scientific communities must be given time to digest the results, and challenged to repeat and thereby confirm them.
  • This is particularly important as the model’s findings may translate into calls for massive increases in spending on HIV treatment and testing programmes, which would reduce future HIV-related costs.
  • The sums necessary to support such programmes are far beyond the means of poor countries. Therefore, rich countries would have to fund these programmes.
  • If the findings of the study are confirmed and supported by the WHO, pilot studies must be mounted to gauge the possibility and sustainability of annual, universal HIV testing and immediate initiation of ART in spite of disease progression. What would be the scale of these pilot studies?
  • Further, detailed research is required to answer the following questions raised by the study’s findings:
  • What are the impacts of initiating immediate life-long ART for all HIV-positive people, irrespective of disease stage?
  • How can methods of ART adherence be improved?
  • How viable is annual, universal HIV testing, and how acceptable would it be to populations?
  • How feasible is universal ART?
  • How will sexual behaviour be influenced?
  • Would the clamour for administrative controls and criminalisation of HIV transmission increase?
  • Some of the study’s assumptions regarding the efficacy and potential scale-up of prevention mechanisms are very ambitious.
  • Current prevention strategies must not be undermined. TAC’s policy on prevention is based on measures which are proven to be effective and which are relatively easy to implement:

o     The use of condoms and clean needles for primary HIV prevention;

o     The use of ARVs for PEP and PMTCT;

o     The scale-up these programmes based on need.

‘€œThe above questions are critical to the course of the HIV epidemic. If we answer these questions while vigorously pursuing current scaling-up and if the study’s recommendations are feasible, Africa and the world would have a very different future,’€ the TAC said.

Professor Helen Schneider of the University of the Witwatersrand’€™s Centre for Health Policy said that the researchers put forward a bold and exciting vision for ‘€œgetting on top of the epidemic’€ within a relatively short period of time

‘€œBut, as all would acknowledge, the gap between such grand visions and their implementation is big; it will take some years to take this model and develop it into a proof of concept,’€ warned Schneider, who is also a member of the SA National AIDS Council.

‘€œPrevention is very urgent now and we need to invest massive resources in current prevention programmes,’€ she said, adding that the Lancet model would require massive societal buy-in to get people tested once a year, and to take treatment for public health purposes rather than individual benefit.

 ‘€œOne needs to ask whether if we invested the same kind of effort (as proposed in The Lancet) in programmes we currently have, whether we wouldn’€™t have similar outcomes,’€ said Schneider.

WHO said in a statement that recommended preventive interventions needed to be maintained and expanded. This includes male circumcision, partner reduction, correct and consistent use of condoms, and interventions targeting most-at-risk populations.

WHO indicated that is would convene a meeting early next year bringing together ethicists, funders, human rights advocates, clinicians,   prevention experts and AIDS programme managers to discuss this and other issues related to the wider use of antiretroviral therapy for HIV prevention.

Geoffrey Garnett and Rebecca Baggaley of the Imperial College London cautioned in their commentary in The Lancet that when early treatment is considered as a prevention tool, success could require substantial resources and depend on a remarkable degree of acceptance and cooperation across populations.

They said the suggested strategy would reflect public health ‘€œat its best and its worst’€.

At its best, the strategy would prevent morbidity and mortality for the population, both through better treatment of the individual and reduced spread of HIV.

At its worst, the strategy would involve over-testing, over-treatment, side-effects, resistance, and potentially reduced autonomy of the individual in their choices of care.

‘€œThe individual might gain no personal benefit from testing and early treatment, but they would benefit from protecting partners ‘€“ and who could object to that, unless they were recklessly exposing others to infection?’€ Garnett and Baggaley asked.

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