Is HIV Getting Weaker? Don't Count On It

World AIDS Day comes with a set of traditions: Local commemorations remember those lost to the epidemic; UNAIDS issues another report on the global impact of HIV; and a handful of celebrities use their big mics to talk about HIV for a day, or even a week (but usually not a lifetime).

There's also the tradition of the "breakthrough" story, where a particular research paper hits the news cycle lottery, captures the imagination of a media-hungry public and often gets exaggerated as far as its implications, importance or impact.

This year's story goes something like this: "HIV is getting weaker."

But is it really? And if it is, what does that really mean for the fight against HIV, and for those who are living with HIV today?

What's the Story?

We summarize the study upon which this story is based on, but here's a quick recap: A newly published study suggests that HIV may be evolving to be less deadly. Natural selection could be "favoring pathogens that cause minimal damage," according to British researchers. The data suggest that HIV is evolving relatively quickly -- and it may be happening faster due to the use of antiretroviral therapy. Over time, it could reduce the capacity of HIV to affect human populations.

The headlines made for good World AIDS Day news: "HIV evolving 'into milder form'" declared BBC News on its website, for example. The stories in the mainstream press -- while they did point out that HIV is still very dangerous -- risked oversimplifying the study and its implications.

This is far from the first study on viral fitness that looks carefully at how HIV is mutating and seeks to calculate what it could mean for the course of the epidemic. In fact, other studies -- including those by some of the same researchers involved in this one -- have done so and gotten different results. Others, including those looking at real-world trends in CD4 counts and viral load, have even concluded that HIV may be getting stronger.

"There might be explanations for these very disparate results, but -- pending additional evidence -- it seems reasonable to maintain a healthy skepticism about all of them," warns Richard Jefferys of Treatment Action Group (TAG).

A few other important caveats most mainstream reports haven't mentioned:

  • The data comes from an analysis of the blood of women living with HIV in Botswana and South Africa, which researchers then used to calculate an estimate of what it could mean over time -- not from direct observation of the health, illness or mortality of the women themselves.
  • The findings do not show that HIV within one individual person's body is necessarily becoming weaker over time. Rather, it could be that the mutated versions of HIV that have been infecting people later in the epidemic rather than earlier in the epidemic's history could be slightly less harmful.

Is This a Big Deal? Is This How AIDS Ends?

According to the study's lead author, Oxford University's Philip Goulder, M.D., the findings are indeed a big deal. As he told the BBC: "You can see the ability to replicate is 10% lower in Botswana than South Africa and that's quite exciting. We are observing evolution happening in front of us and it is surprising how quickly the process is happening. The virus is slowing down in its ability to cause disease and that will help contribute to elimination."

Although he makes a bold assertion about the data's implications, Goulder also issues a caution: "Overall we are bringing down the ability of HIV to cause AIDS so quickly," he told Reuters in a telephone interview. "But it would be overstating it to say HIV has lost its potency -- it's still a virus you wouldn't want to have."

Warner C. Greene, M.D., Ph.D., the director of the Gladstone Institute of Virology and Immunology in California, told that the research does show possible progress. He notes that the primate version of a similar virus evolved to become harmless, but says it will take time for HIV to reach that state -- time we can ill afford in an epidemic that is still raging:

This paper reveals the earliest signs of detente in the dynamic "arms race" that is occurring between HIV and its human host. There is precedence for decreasing virulence of lentiviruses like HIV in the 40 species of African monkeys infected with their own species-specific simian immunodeficiency virus tens of thousands of years ago. In all cases, these simian viruses have evolved to become nonpathogenic -- no AIDS-like illness occurs.

With sufficient time, the same thing will likely happen with HIV ... but we don't have that time to endure the ravages of AIDS which will afflict those who are least able to respond.

TAG's Jefferys is considerably more sanguine, as he explained to

The paper presents interesting findings, but they appear far more tentative than the press hooplah would suggest. The idea that HIV has become less virulent is based on a small difference in results from a laboratory test that attempts to measure how well the virus replicates, and not any information on the CD4 T cell counts or health of study participants over time. A prior research paper found no link between HIV replication capacity measured by this test and the rate of CD4 T cell loss over time, so the lower virus replication capacity reported in the new study may not necessarily be linked to slower disease progression.

What's the Bottom Line?

This is solid science that makes a careful case for what could be an exciting finding if it holds true in other studies and across communities. It adds to the knowledge bank on HIV, and can be held up against contradictory findings in order to finesse where the truth may lie.

However, this level of change in the viral fitness of HIV would only have population-wide impact after many years -- and we can't wait around for HIV to change on its own if we are in the business of ending the epidemic.

For World AIDS Day 2014, UNAIDS released a new analysis on the state of HIV worldwide, in which it asserts that, "If the world does not rapidly scale up in the next five years, the epidemic is likely to spring back with a higher rate of new HIV infections than today."

"We have bent the trajectory of the epidemic," said Michel Sidibé, the executive director of UNAIDS. "Now we have five years to break it for good or risk the epidemic rebounding out of control."

According to UNAIDS, if we want to weaken HIV once and for all, it's going to take more than viral evolution. It's going to take a global effort, including billions of dollars of financial resources and rapid scale-up to reach those in need. UNAIDS says the payoff will be nearly 28 million new HIV infections and 21 million AIDS-related deaths averted by 2030.


Julie "JD" Davids is the managing editor for and