Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:
First Dengue Vaccine Gets Its First Approval, in Mexico
The first vaccine for dengue fever has been approved by Mexico.
Sanofi's Dengvaxia vaccine was approved by Mexican officials to protect people ages 9-45 who live in regions where dengue is common, The New York Times reported.
Mexico is the first country to approve the vaccine.
There is no treatment for dengue, a viral disease transmitted by mosquitoes. It can cause high temperature and intense joint and muscle pain. In severe cases, it can be fatal.
Clinical trials showed the vaccine reduced the risk of developing dengue by about 60 percent, The Times reported.
Estimates about the number of people sickened by dengue each year range from 50 million to 400 million. In recent years, the disease has spread out of its traditional location in developing countries in tropical areas. In 2009, there were cases in the Florida Keys for the first time in decades.
Norovirus Sickened Boston College Students Who Ate at Chipotle
Norovirus, not E. coli, caused 80 Boston College students to become ill after they ate at a Chipotle restaurant, according to health officials.
"Initial testing conducted by the State Public Health has shown the presence of norovirus," said a statement from the health department, NBC News reported.
There was speculation the students were sickened by the same E. coli bacteria that caused 52 people in nine states to fall ill after eating at Chipotle restaurants.
The company said it voluntarily closed the restaurant in the Brighton section of Boston, NBC News reported.
Aspirin Doesn't Help Breast Cancer Patients
Taking aspirin does not improve breast cancer patients' outcomes, according to a study that challenges previous research.
Investigators looked at more than 1,000 breast cancer patients and found that aspirin use was associated with worse outcomes and a lower chance of survival, United Press International reported.
"Past studies have found that aspirin may hold anti-cancer benefits. However, many of them were preliminary, preclinical, and didn't support a clear mortality benefit. They also didn't look at prior use of aspirin," study author Dr. Julia Tchou, associate professor of surgery, University of Pennsylvania, said in a news release.
"Our data did not support the notion that this century-old pill has protective qualities and down-the-road benefits for breast cancer patients. However, larger patient cohort studies are needed to confirm our results," she added.
Another study found that aspirin's effect on breast density may help diagnosis breast cancer at an earlier stage, UPI reported.
Both studies were presented at the San Antonio Breast Cancer Symposium.
Cooling Cap to Reduce Chemo-Linked Hair Loss Approved by FDA
A scalp cooling system that reduces breast cancer patients' hair loss due to chemotherapy has been approved by the U.S. Food and Drug Administration.
The DigniCap is made by Dignitana AB of Sweden. The company will lease the device to cancer centers and patients will be charged a fee for each use, the Associated Press reported.
A half-hour before a chemotherapy session, the patient puts on a tight-fitting cap connected to a cooling machine. The device gradually chills the scalp, which becomes numb by the time chemotherapy infusion begins.
The cooling system is used throughout the treatment and for about an hour and a half after chemotherapy ends, the AP reported.
The DigniCap was tested on 122 early-stage breast cancer patients receiving standard chemotherapy. More than two-thirds of those who used the device kept their hair. Common side effects were cold-induced headaches, neck and shoulder discomfort, and chills and pain, according to the FDA.
Scalp cooling is meant to temporarily reduce blood flow and cell metabolism in the scalp, reducing the amount of chemotherapy drugs that reach and harm hair follicles. Several types of cold caps are available worldwide, the AP reported.
While some question if such devices could prevent chemotherapy drugs from reaching cancer cells in the scalp, the FDA said the chance of that "is extremely rare."
"Because women tend to survive early breast cancer for so many years, the FDA should provide the evidence to show if there's any long-term risk," Dr. Len Lichtenfeld, of the American Cancer Society, told the AP.
Patients should discuss the use of the cooling cap with their doctors, he advised.
No Change in U.S. Life Expectancy for Third Year in a Row: CDC
Americans' life expectancy did not increase for three years in a row, a federal government report says.
A child born in 2014 can expect to live 78 years, 9 1/2 months, the same as those born in 2013 and 2012, according to the Centers for Disease Control and Prevention.
Medical advances, improved nutrition and education and public health campaigns have helped Americans' life expectancy rise in most years since World War II. The last time it remained stagnant for three consecutive years was in the mid-1980s, the Associated Press reported.
The reasons for the latest multi-year stall aren't clear, but some experts believe drug overdose deaths and suicides may play a significant role.
The obesity epidemic and other factors have led some to wonder if life expectancy in the U.S. will peak, but there is no evidence that is occurring now, according to the CDC.
One expert who agrees is S. Jay Olshansky, a public health professor at the University of Illinois-Chicago. "It's too early to tell. Three years does not a trend make," he told the AP.
The World Bank says life expectancy in the U.S. is lower than in nearly 40 other countries. Those at the top of the list are Japan and Iceland, where people can expect to live past age 83.
The CDC report also said infant deaths in the U.S. fell again to a record low of 5.8 per 1,000 births, the AP reported.
In 2014, there was no change in the top 10 causes of death in the U.S., which are heart disease, cancer, respiratory diseases like emphysema and bronchitis, accidents and unintentional injuries, stroke, Alzheimer's disease, diabetes, flu and pneumonia, kidney disease and suicide.
There were large drops in rates of death from five causes, including heart disease and cancer. The largest increase (8 percent) was for Alzheimer's disease. Deaths from suicides and accidental injuries -- including drug overdoses, traffic crashes and falls -- rose about 3 percent, the AP reported.
CDC Tests Fail to Detect E. Coli in Onion/Celery Mix Used in Costco Chicken Salad
The presence of E. coli in the onions and celery mix used to make Costco chicken salad linked to a multi-state E. coli outbreak could not be confirmed in further testing, the Centers for Disease Control and Prevention said Tuesday.
However, the agency also said the mix from Taylor Farms Pacific has not been ruled out as the source of E. coli that sickened 19 people in seven states, the Associated Press reported.
And public health officials in Montana who conducted the initial tests also said the CDC's results don't mean their earlier findings were invalid.
Fragments of DNA from E. coli bacteria were definitely found in the samples they tested, said Jim Murphy, chief of the Communicable Disease Bureau in the state's health department, the AP reported.
The onions and celery mix has been recalled by Taylor Farms.