Four things you should know about the HIV "cure" before you get too excited

The baby might not even have been infected in the first place.

The story everyone is talking about today is the HIV "cure" - the Mississippi baby who, after being blasted with a cocktail of anti-viral drugs at birth, is now, at two years old, apparently virus-free. But when reading the euphoric news stories about it here, here and here, you should bear the following in mind:

1. The baby may not even have been infected in the first place

Here's a weird section in the NYT version of the story. Have a read of the following two paragraphs - are the doctors certain or uncertain that the baby was infected?

“The one uncertainty is really definitive evidence that the child was indeed infected,” said Dr. Daniel R. Kuritzkes, chief of infectious diseases at Brigham and Women’s Hospital in Boston.

Dr. Persaud and some other outside scientists said they were certain the baby — whose name and gender were not disclosed — had been infected. There were five positive tests in the baby’s first month of life — four for viral RNA and one for DNA. And once the treatment started, the virus levels in the baby’s blood declined in the pattern characteristic of infected patients.

The tests are pretty good, but are not usually trusted as a basis for confirmed diagnosis at that early stage. It is normal practice to confirm positive tests at 6 weeks. But as this baby had already been treated by then, lowering its viral load (negative tests came back at 29 days), it would have been difficult to do this. There is a very small chance the baby was not infected.

The virus may not have yet taken a hold on the baby's cells in a permanent way. Here's the WSJ:

Cells in the baby "may have been infected—there was virus around," said Steven Deeks, an AIDS researcher at University of California at San Francisco. "But the cells being infected weren't the type that become long-lived reservoirs."

There is also a small chance the baby was immune to HIV anyway. Around 1 per cent of Caucasians in the US are naturally immune.

Now, these are small chances, but then this baby is an outlier. It was not part of a large study where such anomalies are ruled out. The scientists have said it is unlikely to be replicable. Any way you put it, the baby itself is an anomaly.

2. This "cure" has already been found, and has been used on newly-infected people since 1987. Even if the baby was infected, today's news would simply extend it to newborns.

Today's news applies only to babies. Newborns at that. And it's not really a new method - rather, it's the same idea as PEP: if you have only just been infected, you might avoid HIV if you are immediately given a large amount of anti-HIV drugs. What the scientists confirmed today is that, in terms of emergency treatment, newborns are the same as newly-infected people. 

Here's the NYT again:

“That goes along with the concept that, if you treat before the virus has had an opportunity to establish a large reservoir and before it can destroy the immune system, there’s a chance you can withdraw therapy and have no virus,” said Dr. Anthony S. Fauci, the director of the National Institute for Allergy and Infectious Diseases.

(Oh, and if you were wondering, someone has actually been cured of AIDs before. This was a man called Timothy Brown, a leukemia sufferer who received a bone-marrow transplant from a donor genetically resistant to HIV.)

3. This would not be breaking much ground in preventing HIV in newborns anyway, because we have a solution for that

In countries with access to top-notch medical care (ie western countries), the transference of HIV from mother to child is extremely rare. This is because mothers are treated with antiretroviral therapy during pregnancy - a very effective way of preventing HIV in newborns.

4. Newborns in countries without a solution for that probably wouldn't get this treatment anyway

In countries without access to top-notch medical care, there is no reason that this treatment would be available where antiretroviral pregnancy treatment isn't.

So what does the news mean? Well it means that a few babies in countries with access to this sort of care but whose mothers have somehow slipped through the net of normal practice can be saved. Joyous news. But not quite as joyous as everyone seems to be making out.

UPDATE: This blog originally said that HIV tests at birth couldn't be accurate, but this applies only to antibody tests. The tests on DNA/RNA, which were done in this case, have a greater (although not 100 per cent) degree of accuracy.

HIV cure: not necessarily.. Photograph: Getty Images

Martha Gill writes the weekly Irrational Animals column. You can follow her on Twitter here: @Martha_Gill.

Photo: Getty
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Space suicide: the sad but noble death of the Cassini probe

It’s not surprising that scientists and space geeks around the world will bid it adieu with a heavy heart.

Since April 2016, a Twitter bot called @CassiniNoooo has been tweeting out “Nooooo” followed by random numbers of “O”s. The last tweet sent by the bot is just “I......”.  

The account has been paying a light-hearted tribute to one of the most important important scientific projects of recent times, and one which is soon to come to an end. 

Launched in 1997, Cassini-Huygens is a plutonium-powered probe that has been circling Saturn since 2004. Providing teams of scientists with unparalleled images of Saturn and its moons, it has allowed experts to examine the composition of solar bodies one billion miles away.

But on 15 September, Cassini will begin its final mission, referred to by Nasa scientists as its "Grand Finale". It will shed its modules and sensors as it heads towards a final fiery death in Saturn's gaseous atmosphere.

When news of Cassini's impending end was announced in April, scientists, casual space fans, engineers, teachers and other assorted stargazers expressed sadness about the craft’s suicide mission. Many are expected to tune in to watch the live stream of the probe's final moments on Nasa’s dedicated webpage

Cassini has provided some of the most intriguing discoveries about our solar system. It discovered a saltwater ocean under the icy surface of one of Saturn’s moons, Enceladus, by "tasting" molecules – a finding that could, in theory, support alien life. It also took photographs of Titan, a moon bigger than Mercury, which enabled scientists on earth to discover liquid on its surface – only the second body in the universe to have free-standing liquid after our own planet. 

In a way, Cassini's discoveries signed its own death warrant. Potentially life-supporting pristine environments must not be contaminated by Earth-originating microbes and, left to its own devices, Cassini could collide with one of the moons it discovered so much about.

Faithful until its last moment, Cassini will be diving in and out of the space between Saturn and its rings as it reaches the end of its final orbit, a feat never achieved before, transmitting completely novel data that would be too risky to gather unless it was already destined for immolation.

Cassini's contribution to science, laid out in this oddly moving webpage from Nasa, not only allowed us a deeper understanding of our solar system, but also helped us picture other kinds of worlds. It's a service that has been recognised well beyond academics or professional scientists. One six-year-old is even throwing Cassini a goodbye party, with a themed cake and games – because, he said, it was the “only spacecraft he ever knew”. Others have tweeted out music composed for Cassini, and comics depicting their versions of its final moments.

It has not been easy for the scientists who had to approve the decision to kill Cassini. In a press conference on 4 April, roughly three weeks before Cassini started its final orbit, Linda Spilker, a planetary scientist at Nasa's Jet Propulsion Laboratory, admitted that it was hard to say goodbye to their “plucky, capable little spacecraft”. Some even referred the probe as their child.

On Earth, we get to think of these robotic explorers like astro-ambassadors, not least because so much of the current discussion around space monitoring centres on how information collected will enable life in space for humans. Now one of those ambassadors is about to make its final visit to a foreign planet, long before its creators will get to make their own introductions.