Richard Knox

After decades of intense effort, an effective vaccine against HIV is not on the horizon — and, some say, may never be possible. So some AIDS researchers are going passive.

As in passive immunization.

Active immunization is what an effective vaccine does. It stimulates the recipient to make antibodies that protect against a disease. Passive immunization involves the direct injection of antibodies extracted from survivors of a particular infection.

It was 11 on a Tuesday night nearly six years ago when Jean-Clair Desir's mother fell ill with cholera in the Boucan-Carre district of Haiti's central highlands.

"She started vomiting with diarrhea," Desir recalls. "I made oral rehydration for her, nothing worked. She died at 3 in the morning." She never made it to a hospital or clinic and so probably wasn't counted as a cholera victim.

After burying his mother, Desir, a third-year student at Haiti's University of Agronomy Sciences, nearly died of cholera himself.

Mike Quaglia was 42 when he was diagnosed with Parkinson's disease, which gradually robs its victims of their ability to move normally. For the next seven years, his condition deteriorated despite medication.

"I was at a point where I was either going to give up and let the Parkinson's take over, or I was going to decide to fight back," Quaglia says.

Fight back he did — literally. Last February he stumbled on a program called Rock Steady Boxing. That's right: It teaches Parkinson's patients how to box.

Haiti's magnitude 7.0 earthquake of Jan. 12, 2010, left 220,000 people dead, 300,000 injured and rubble nearly everywhere.

The catastrophe also unleashed an unprecedented flood of humanitarian aid — $13.5 billion in donations and pledges, about three-quarters from donor nations and a quarter from private charity.

But today Haiti is a long, long way from realizing the bullish goal of "building back better."

Authors of the first-ever global guidelines for treating hepatitis C went big Tuesday, advocating for worldwide use of two of the most expensive specialty drugs in the world.

The new guidelines from the World Health Organization give strong endorsement to the two newest drugs. Gilead Sciences' Sovaldi costs $1,000 per pill, or $84,000 for a 12-week course of treatment. Olysio, sold by Johnson & Johnson's Janssen Pharmaceuticals unit, costs $66,360 for a three-month course.

When sweeping new advice on preventing heart attacks and strokes came out last November, it wasn't clear how many more Americans should be taking daily statin pills to lower their risk.

A new analysis provides an answer: a whole lot. Nearly 13 million more, to be precise.

Colorado opened its first pot stores in January, and adults in Washington state will be able to walk into a store and buy marijuana this summer. But this legalization of recreational marijuana is taking place without much information on the possible health effects.

Scientists have gotten close to pinning down the origin of Middle East Respiratory Syndrome, a dangerous respiratory disease that emerged in Saudi Arabia 17 months ago.

It turns out the MERS virus has been circulating in Arabian camels for more than two decades, scientists report in a study published Tuesday.

So far MERS has sickened more than 180 people, killing at least 77 of them — an alarming 43 percent. But scientists haven't been sure where the virus came from or how people catch it.

As flu-watchers like to say, you can always count on influenza virus to surprise.

The latest revelation is that scientists have apparently been wrong about where new flu viruses come from. The dogma is that they always incubate in wild migratory birds, then get into domestic poultry, and then jump into mammals — especially pigs and humans.

A Pennsylvania county judge has thrown out an assisted suicide case against a 58-year-old nurse named Barbara Mancini, who was accused of homicide last year for allegedly handing her 93-year-old father a bottle of morphine.

An effective new medicine is developed as a cure for a major disease. The drug company prices the medicine at tens of thousands of dollars for a course of treatment. How can the disease-curing medicine be made accessible to patients who need it, most of whom live in low- and middle-income countries?

There's new evidence that widely prescribed testosterone drugs — touted for men with flagging libidos and general listlessness — might increase the risk of heart attacks.

A study of more than 55,000 men found a doubling of heart attack risk among testosterone users older than 65, compared with men who didn't take the drug.

As China gets ready to usher in the Year of the Horse on Friday, millions of them will find it hard to buy chicken for traditional Lunar New Year feasts. That's a mark of the nation's growing anxiety about a poultry-borne flu virus called H7N9.

On Tuesday, Hong Kong agricultural workers will begin destroying 20,000 chickens. The bird flu virus H7N9 was found in a single live bird from a farm in neighboring Guangdong Province.

Go into almost any hospital these days and you'll hear a constant stream of beeps and boops. To most people it sounds like medical Muzak.

But to doctors and nurses, it's not just sonic wallpaper. Those incessant beeps contain important coded messages.

Acting Surgeon General Boris Lushniak is the latest in a long line of surgeons general who have tried to pound the final nails into the coffin of America's smoking habit.

When you take a pill, you and your doctor hope it will work — and that helps it work.

That's not a new idea. But now researchers say they know just how much of a drug's effect comes from the patient's expectation: at least half.

When patients in the midst of a migraine attack took a dummy pill they thought was a widely used migraine drug, it reduced their pain roughly as much as when they took the real drug thinking it was a placebo.

Saturday marks an important milestone in public health – the 50th anniversary of the first Surgeon General's Report on Smoking and Health.

Few if any documents have had the impact of this one — both on the amount of disease and death prevented, and on the very scope of public health.

Federal regulators this month opened a new era in the treatment of a deadly liver virus that infects three to five times more people than HIV. Now the question is: Who will get access to the new drug for hepatitis C, and when?

The drug Sovaldi will cost $1,000 per pill. A typical course of treatment will last 12 weeks and run $84,000, plus the cost of necessary companion drugs. Some patients may need treatment for twice as long.

Enrollment is picking up in new health insurance marketplaces. But the 365,000 who've signed up as of November 30 is a fraction of just one high-visibility group – those whose previous insurance has been cancelled because it didn't meet Affordable Care Act standards.

They're people like Doug Normington, a 58-year-old self-employed videographer in Madison, Wis., who has struggled to buy new insurance since late October.

Researchers say they are achieving success in curing the genetic defect that causes some children to be born without immune defenses, a rare condition made famous in the 1970s by a Texas boy who lived most of his short life in a sterile "bubble."

Scientists now report that 8 out of 9 young children given gene therapy for a type of severe combined immunodeficiency disease, called SCID-X1, are alive and living amid the everyday microbial threats that would otherwise have killed them. The oldest is just over 3 years old.