Featured news from NHIVNA
HIV-related news from NAM
Model suggests HIV vaccine still has key role in ending AIDS
Liz Highleyman, 2016-01-25 08:00:00
Even a modestly effective HIV vaccine would likely be
cost-effective and could make a major contribution to a sustainable response to
the global HIV/AIDS epidemic, especially in combination with the scale-up of
other interventions including prompt initiation of antiretroviral therapy (ART) and
pre-exposure prophylaxis (PrEP), according to a report in the January 5 edition of PLoS ONE.
including condoms, antiretroviral treatment as prevention (TasP) and PrEP have
already brought about substantial reductions in new HIV infections, but there
are still too many people becoming infected worldwide to bring the epidemic to
Thomas Harmon of the
International AIDS Vaccine Initiative (IAVI) and colleagues performed a modelling
study to estimate the impact of an HIV vaccine, combined with interventions
included in the UNAIDS Investment Framework Enhanced (IFE), in low- and
The IFE, proposed in 2013, explored how maximising existing interventions and adding emerging prevention options could reduce new HIV infections and AIDS-related deaths in low- and
middle-income countries, the authors noted as background. This report describes
additional modelling that looked more closely at the potential health impact
and cost-effectiveness of HIV vaccines.
The researchers devised an
epidemiological model to explore the potential impact of HIV vaccination in
low- and middle-income countries in combination with other interventions
through 2070. Sensitivity analyses looked at variations in vaccine efficacy,
duration of protection, coverage and cost.
The model looked at three possible scenarios:
- Current trends - assumes that incremental linear scale-up of ART and prevention of
mother-to-child transmission from 2010-2013 continues, off-setting the natural
increase in new infections due to population growth and resulting in a
steady annual incidence; eligibility for ART remains at <350 cells/mm3
and ART coverage is capped at 80%. (Current WHO guidelines call for
treatment for everyone with HIV regardless of CD4 count, but this has not
yet been implemented in many countries.)
- 50% scale-up of IFE - assumes that UNAIDS IFE targets are only achieved halfway, based
on linear scale up from 2013 coverage to 50% of IFE target levels in 2020.
- Full scale-up of IFE - assumes that the IFE targets are fully achieved, based on linear
scale up from 2013 to the target levels in 2020.
In the currenttrendsscenario, incremental scale-up
of existing interventions results in a flat trajectory of new infections in low- and middle-income countries, with around 1.6 million annually in 2070. 50%
scale-up of IFE would reduce the number of new annual HIV infections
to approximately 1 million in 2070, and if UNAIDS IFE goals were fully
achieved, new annual HIV infections would decline to 550,000 in 2070.
Adding a three-dose HIV vaccine with 70%
efficacy, five years of protection and high coverage, introduced in 2027 along
with the full scale-up scenario, would reduce annual infections by 44% over the
first decade, by 65% over the first 25 years and by 78% (to around 122,000) in
2070. Under the same scenario a vaccine with 30% efficacy would reduce new
infections by 44% (to around 306,000) while a vaccine with 90% efficacy would
produce a 87% reduction (to around 74,000) by 2070.
Adding the same 70% effective vaccine to the
current trends scenario would reduce new infections by 85% (to around 260,000)
and adding it to the 50% scale-up scenario would reduce incidence by 82% (to
around 184,000) by 2070. That is, the impact of the vaccine would be greater if
the IFE targets were not fully achieved, according to
Adding PrEP, TasP and an HIV vaccine -
individually or in combination - to the full
IFE scale-up scenario would reduce the number of annual new HIV
infections in 2070 by 29%, 34%, 78% and 91%, respectively, with vaccination
providing the strongest single benefit despite being introduced later. A
combination of PrEP, TasP and a vaccine could reduce the number of annual
infections to around 49,000 in 2070.
The researchers also presented evidence showing
than an HIV vaccine would be cost-effective under a wide range of scenarios.
"Even a modestly effective vaccine could
contribute strongly to a sustainable response to HIV/AIDS and be
cost-effective, even with optimistic assumptions about other
interventions," the study authors concluded. "Higher efficacy would
provide even greater impact and cost-effectiveness, and would support broader
"First generation AIDS vaccines may not
achieve the very high efficacy levels of most other currently licensed
vaccines, and structural, cultural and social barriers may make it challenging
to meet assumed coverage rates for some target populations," they caution,
"but the model shows that vaccines of relatively lower efficacy and uptake
still have the potential to substantially reduce new HIV infections."
"The data suggest that under certain
circumstances vaccination could prevent more new infections with HIV than other
new prevention options," they wrote. "However, the modelling also
confirms that no single option can solve the problem alone. A variety of
prevention and treatment options can complement each other in ensuring that the
specific needs of specific populations in different circumstances are met in
order to maximize the reduction of new HIV infections."
"These new analyses
underscore the powerful potential of an AIDS vaccine to help save and improve
the lives of millions in a cost-effective manner," IAVI president and CEO Mark Feinberg stated in a press release. "It is clear that we must continue to expedite
development of an effective HIV vaccine alongside the critical efforts to
accelerate and sustain broad and equitable access to effective antiretroviral
therapy and new approaches for pre-exposure prophylaxis."