More primary care doctors in a community (社区) appear to lead to improved life expectancy for people living there，though a lack of such physicians across U.S. could be a cause of concern for overall population health in years to come.

For the study, researchers looked at physician counts per 100,000 people in a range covering 2005 to 2015 in the U. S.，along with life expectancy and specific causes of death. They found that an increase of 10 primary care physicians per 100,000 population was associated with a 51. 5-day increase in life expectancy, while an increase of 10 specialty physicians per 100, 000 population increased life expectancy by 19. 2 days. An increase in primary care physicians also was associated with reductions of many deaths including heart diseases and cancers.

Along with those findings, though, the study said many communities did not have primary care physicians in 2015，with the decline in supply more prominent in rural areas than their urban areas. Many believe that a well-functioning health care system requires a solid foundation of primary care, however, payment difference between primary care and technical specialties continue to dispirit the U. S. primary care physician workforce.

“Higher pay and lifestyle preferences lead most students to choose non-primary care fields, even when their hearts say primary care,” the study said. “We must turn this trend around with practical changes in physician payment policy; no amount of superb primary care training or creative practice reform will prevent further declines in primary care physician, which will lead to worsening health for the United States. ”

The study’s researchers conclude that future research should focus on the “quality and cover of primary care，types of primary care physician training and service offerings, and effective access rather than just supply”.

AIDS-related illnesses have killed more than 30 million people since 1981. That's half as many deaths as in World War II. And it's not over. An estimated 1.1 million Americans are among the 33 million people worldwide who are now living with HIV, the virus that causes AIDS.

Between 1884 and 1924, somewhere near modern-day Kinshasa in West Central Africa, a hunter kills a chimpanzee. Some of the animal's blood enters the hunter's body, possibly through an open wound. The blood carries a virus harmless to the chimp but deadly to humans: HIV.

In June, 1981, the CDC publishes a report from Los Angeles of five young homosexual men with fatal or life-threatening PCP pneumonia. First cases recognized. In 1985, Rock Hudson dies of AIDS. Larry Kramer's AIDS play, "The Normal Heart." shocks New York audiences.

In 1986, for the first time, President Reagan publicly utters the word "AIDS." In 1987, Princess Diana is photographed hugging people with AIDS. Reagan makes his first speech on AIDS. Liberace dies of AIDS. Three years later, Photographer Robert Mapplethorpe dies of AIDS.

In 1988, the first World AIDS DAY is held on Dec. 1. During 1991-1992, the red ribbon is introduced as a symbol of AIDS solidarity(团结一致). But AIDS becomes the leading cause of death in U.S. men aged 25-44 and ten years later, AIDS becomes the leading cause of death worldwide for people aged 15 to 59.

In 2008, for the first time, global AIDS deaths decline. UNAIDS calculates that the global spread of AIDS peaked in 1996 at 3.5 million new infections. Deaths peaked in 2004, at 2.2 million. Yet AIDS Day 2009 brings surprising figures: 2.7 million new HIV infections and 2 million AIDS deaths in the previous year.

Researchers have discovered more than a dozen antibodies that target the HIV virus. They hope that these discoveries will lead to a vaccine that offers long-term protection against AIDS. One antibody in particular, PGT 128, is considered among the most potent and promising—preventing about 70% of viruses from infecting cells in laboratory tests.

When you are sick, you may dream: if only I had been given an injection against diseases before my birth. It is not a dream now.

On Nov. 26, He Jiankui from Guangdong announced the birth of healthy twin girls, Lulu and Nana, earlier in the month. They came into being via external fertilization with gene editing technology that protected them from HIV infection.

The reaction to his announcement was explosive. China’s Ministry of Science and Technology has cooperated with other departments to investigate He’s project. In a signed open letter released on Nov. 27, 140 Chinese researchers in HIV/AIDS from China and abroad condemned the research. They questioned the need for He’s project. The letter said that there are many treatments that prevent babies born to HIV-positive parents from being infected. In fact, there are many drugs for this.

Until now, there has only been gene editing research on faulty embryos(胚胎）. The research only went ahead when it was clear that children would have terrible diseases. But even this research is controversial.

The idea that research could find ways to switch off genes that cause cancer may be exciting, but it is also troubling. There are worries about babies that are designed to be superior, with better looks and above average skills. People are also concerned that gene editing changes the human genome(基因组）, which means that changes will be handed onto future generations and spread through the population. Such research also raises ethical(道德的）questions. If the technology becomes available, who will be able to use it? Will it be only the wealthy? And if people live much longer lives, will there be an effect on the size of the world population?

Those questions are difficult to answer. But one thing is certain: If the cures have the potential to affect not just those who are treated, but the human population as a whole, it’s important to ensure that scientific advances aren’t getting too far ahead of our understanding of how to use them.