Jon Cohen

IL-12 Deaths: Explanation and a Puzzle

Researchers investigating toxic reactions that killed two patients in a trial of interleukin-12 earlier this year have reached a surprising conclusion: The drug is highly toxic if it is given in multiple high doses, but those effects can be avoided if the multiple doses are preceded by a single dose followed by a rest period. The initial dose apparently imprints a memory on the immune system, but the mechanism is unclear.

HIV Treatment as Prevention

Breakthrough of the YearHIV/AIDS researchers have long debated whether antiretroviral drugs (ARVs) used to treat HIV-infected people might have a double benefit and cut transmission rates. To some it was obvious: ARVs reduce HIV levels, so individuals should be less infectious. Skeptics contended that this was unproven. Then in May of this year, the 052 clinical trial conducted by the HIV Prevention Trials Network (HPTN) reported that ARVs reduced the risk of heterosexual transmission by 96%. Because of HPTN 052s profound implications for the future response to the AIDS epidemic, Science has chosen it as its Breakthrough of the Year.

Approval of Novel TB Drug Celebrated—With Restraint

The U.S. Food and Drug Administration approved the drug, bedaquiline, for only patients who have multidrug-resistant tuberculosis, which can require up to 2 years of treatment. It is the first new tuberculosis drug to be green-lighted in more than 40 years, but the celebration was tempered as sobering challenges face the drug9s wide scale use.

Painful Failure of Promising Genital Herpes Vaccine

A vaccine designed to ward off genital herpes has failed in a large clinical trial, abruptly ending the product9s seemingly promising future. After 8 years of study in more than 8000 women in the United States and Canada, there was not even a hint of a positive result against the sexually transmitted disease caused by herpes simplex virus-2.

As Swine Flu Circles Globe, Scientists Grapple With Basic Questions

On 27 April, 6 days after the U.S. Centers for Disease Control and Prevention (CDC) first reported an unusual swine flu outbreak in humans, international agencies were still struggling to determine how serious a threat the virus posed. Shortly after CDC rang the alarm bell on 21 April in a Morbidity and Mortality Weekly Report dispatch about two cases of swine flu in southern California, scientists and health officials around the world went on alert, concerned that this never-before-seen virus could lead to a killer pandemic. They quickly determined the genetic sequence of the virus, linked the U.S. cases to an apparently much larger outbreak in Mexico, and began fashioning international and local responses. But some say the world hasn9t done nearly enough over the past 10 years to prepare for a pandemic.

Microbicide Fails to Protect Against HIV

HIV prevention research suffered another setback this week with the failure of the largest trial yet of a microbicide used by women to prevent sexual transmission of the virus.

Out of Mexico? Scientists Ponder Swine Flu's Origins

The origin of the virus behind the current swine flu outbreak, its muscle power, and how much of a threat it presents remain mysteries. After Mexico, the United States has had the most cases, which on 5 May totaled 403. The almost simultaneous confirmations of the outbreak in both Mexico and the United States initially added further confusion to the outbreak9s origins. But the virus itself has helped clear up some matters. The greatest concern is what will this confusing virus, which combines genes from swine, avian, and human influenza strains, do next?

The Emerging Race to Cure HIV Infections

Four years after Timothy Ray Brown received bone-marrow transplants to fight leukemia, the most sophisticated labs in the world cannot find any trace in his body of the HIV that had infected him for 12 years. Brown is the only living human, a growing consensus contends, to be cured. Brown9s treatment clearly does not offer a road map for many others. After all, the expensive, complex, and risky transplant only made sense because Brown was dying from leukemia. Nor is it clear exactly which components of the extensive transplant regimen cleared the virus from his body. But Brown9s case has moved the much-ridiculed idea of curing HIV onto the most scientifically solid ground it has yet occupied, say leading AIDS researchers. Brown9s case showed for the first time that it is possible to rid the body of the virus—even from the minuscule reservoirs where the virus can hide out for years, evading both the immune system and antiretroviral drugs (ARVs). His astonishing turnaround also raised hopes that other, more practical drugs and immune system modulators might find and destroy every last bit of virus—or at least reduce it to such low levels that people no longer need ARVs.

The Novel H1N1 Influenza

For years, scientists have been warning about the potential for an influenza pandemic on the order of the 1918 Spanish flu. They imagined the culprit would surface in Asia—and, since 2003, have worried that the avian influenza strain H5N1 might be it. Health officials worldwide drafted one preparedness plan after another. But the pandemic that erupted last spring looks nothing like the one in the plans. Not only did it begin in North America, but the swine virus behind it is a novel form of an H1N1 strain already circulating in humans. And although the new H1N1 is unusually dangerous for the young and for pregnant women, in most otherwise healthy people it causes a disease no more severe than seasonal flu. Scientists have repeatedly warned that this relatively mild virus could mutate or swap genes with cousins and become deadlier. But for now, it looks as if this H1N1 will go down in history more for causing confusion than catastrophe.

Ebola vaccine trials raise ethical issues

The Ebola virus keeps spreading in West Africa and some researchers say that a vaccine is necessary to halt the epidemic. The two most advanced candidates have recently entered safety trials, and if they do not cause harm and trigger the immune response scientists hope to see, the World Health Organization (WHO) has recommended jumping straight into what amount to phase III efficacy tests in Liberia, Guinea, and Sierra Leone. But difficult questions are now emerging about how to design clinical trials, who should be the first to get the shots, and when to begin mass production. For instance, at a consultation held by WHO, there was broad support for randomized controlled trials. But some, like Doctors Without Borders, say such a trial, in which some subjects are assigned to a control group that doesn9t receive the actual vaccine, is unethical.