Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

Fourth Person in China Dies of H7N9 Bird Flu

A fourth person in China has died from the H7N9 strain of bird flu, state-run TV announced Thursday.

It said the number of known human cases of H7N9 in China is now 11, CNNreported. Until now, this strain of bird flu had not infected people.

No details about the latest victim were immediately available. The three previous victims included two men, aged 27 and 87, in Shanghai and a 38-year-old man who lived in Zhejiang province but worked in nearby Jiangsu province, said the state-run news agency Xinhua.

Chinese officials are trying to pinpoint the source of the human infections, CNNreported.


Walgreen Clinics Will Offer Chronic Disease Care

Chronic diseases such as diabetes, high blood pressure and asthma have been added to the types of health issues seen at Walgreen drugstore clinics.

The company said Thursday that most of its 370 in-store Take Care Clinics will diagnose, treat and monitor patients with certain chronic illnesses that are typically handled by doctors, the Associated Pressreported.

A few years ago, most CVS Caremark Corp. MinuteClinics began handling chronic conditions.

Drugstore clinics are run by nurse practitioners or physician assistants. They have become increasingly popular as a convenient way for patients to get care when their regular doctor is unavailable, the APreported.


New Research May Help Lead to HIV/AIDS Vaccine

In what may be an important advance in efforts to develop an HIV vaccine, scientists have analyzed one person's immune response to the virus to determine how a series of mutations created an antibody that can conquer many strains of HIV, which is the virus that causes AIDS.

The team examined numerous sequential samples of blood from an African man. The samples were collected from shortly after he was infected with HIV until about two years later, when his immune system began to produce "broadly neutralizing antibodies" against HIV, The New York Timesreported.

The antibodies produced by the man's immune system were able to defeat about 55 percent of all known HIV strains, according to the study published online in the journal Nature.

While an HIV vaccine still remains far off, this research could prove important in attempts to reach that goal.

"The beauty of this is that it's a big clue as to the sequential steps the virus and the antibody take as they evolve," said Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, which financed the research, The Timesreported.

Experts reacted cautiously to the study.

The findings are "a road map to vaccine development, yes -- but it's like one of those maps of the world from the year 1400. We still don't know how to turn this into a vaccine," Dr. Louis Picker, an HIV vaccine specialist at Oregon Health & Science University, told The Times.

It's not clear if one patient's immune process could be applied to others, noted Dr. Joseph McCune III, head of experimental medicine at the University of California, San Francisco.

One major reason why efforts to create an HIV vaccine have so far failed is because the virus mutates so rapidly. Flu viruses mutate so often that flu vaccines must be reformulated every year. In one day, HIV mutates as much as flu viruses do in a year, The Timesreported.

Worldwide, 34 million have HIV and 2.5 million are newly infected each year, including 50,000 in the United States.