From the elimination of measles in the U.S. to the advance of potential new treatments for Alzheimer's disease, 2016 was a jam-packed year for health news.
Here are eight of the most noteworthy health news stories from this year:
Zika's rise and retreat
Although the Zika virus was identified in 1947, it erupted onto the world scene in 2015, and moved into greater global consciousness with lightning speed over the past year.
During the summer of 2016, local transmission of the Zika virus was seen in the U.S. for the first time, in a neighborhood near Miami. And in August, the National Institutes of Health announced that it had launched a clinical trial to test a vaccine to protect people against Zika infections.
These infections can be hard to spot, Dr. Robert Glatter, an emergency physician at Lenox Hill Hospital in New York City, told Live Science. That's because 80 percent of people infected with the virus have no symptoms, and the other 20 percent usually have only mild symptoms, like fever and headaches, he said.
The primary danger of the virus, though, comes from the potential birth defects Zika causes when it infects pregnant women: Researchers have linked the virus to microcephaly, a disorder in which babies are born with smaller-than-average heads. These babies then face lifelong disabilities.
On Nov. 18, 2016, the World Health Organization declared that Zika was no longer a global emergency. Even still, the virus has spread to the U.S. in areas like Florida and Texas, where Zika-infected mosquitoes now exist. Currently, no vaccine for Zika exists.
"Zika is here to stay in the Americas. It's going to be a part of our lives for years to come," Glatter told Live Science in February. "We need to look at the time line and get a good idea of what the viruses are that are a threat to the human race, and invest in technologies and spot the trends early to become more proactive and less reactive."
Advance in Alzheimer's treatment
An advance in the search for a treatment for Alzheimer's disease hit the stage in 2016: An early study, published in August, found that an investigational drug called aducanumab can significantly reduce the amount of amyloid beta plaque in the brains of Alzheimer's patients. This plaque consists of the tangled clumps of proteins that build up over time in the brains of people who have Alzheimer's disease. The researchers concluded that the drug spurs the immune system to work to clear the plaques.
Although the study was not designed to show whether the drug can improve people's cognitive abilities, the findings suggest that the drug does work this way, the researchers said.
"We believe that's a hint of efficacy," study co-author Dr. Alfred Sandrock said during a news briefing on the findings. Sandrock is a neurologist and executive vice president at Biogen, the Cambridge, Massachusetts, company that funded the trial and applied to patent the drug.
More research is needed to determine whether the drug affects patients' symptoms of Alzheimer's, Sandrock said.
Ebola outbreak declared over
Earlier this year, the World Health Organization (WHO) declared that the Ebola outbreak in West Africa was no longer a Public Health Emergency of International Concern, signifying that the region was largely clear of the disease. The outbreak began in December 2013 and raged during 2014 and 2015, striking hardest in Guinea, Liberia and Sierra Leone, where more than 28,000 people were infected. More than 11,000 people in the region died from the disease.
Dr. Bruce Aylward, WHO's special representative for the Ebola response, noted in a statement in January 2016 that efforts to prevent and track the disease were still underway, and that "we still anticipate flare-ups and must be prepared for them.
Landmark Supreme Court case in women's health
On June 27 this year the Supreme Court overturned a Texas bill that had stated that doctors who perform abortions must have admitting privileges at a nearby hospital. The majority opinion (decided 5-3) said that such requirements did not offer any medical benefits to women seeking abortions, given that "abortion is one of the safest medical procedures performed in the United States."
Patients who undergo the procedure in a clinic rarely require hospital admission, said the American Congress of Obstetricians and Gynecologists.
Controversy over the EpiPen
This year, the EpiPen's skyrocketing price generated controversy. The device allows people to inject epinephrine into their systems to counteract life-threatening allergic reactions. But in 2016, the device's price had increased by 500 percent since 2009. Mylan, the company that sells EpiPens, agreed in October to pay a whopping $465 million to the Department of Justice (DOJ) after accusations that it had been overcharging Medicaid for the devices. As part of that settlement, Mylan did not have to admit to any wrongdoing, but worked with the Department of Justice to create a corporate integrity agreement.
Mylan CEO Heather Bresch said in a statement to the U.S. House of Representatives in September that "the misconception about our profits is understandable and at least partly due to the complex environment in which pharmaceutical prices are determined."
She also detailed Mylan's plans to offer savings to EpiPen consumers, including offering the first generic version of the EpiPen.
Americans voted on weed in the election
During the 2016 election, Americans in nine states voted on whether to legalize marijuana, for either medical or recreational use, in their states. Now, it's legal to recreationally use marijuana in Alaska, California, Colorado, Oregon, Maine, Massachusetts, Nevada, Washington and the District of Columbia. Plus, 21 other states allow people to use marijuana for medical purposes.
It's hard to say yet what effect all of the new laws might have, experts said. Dr. Tina Rizack, an oncologist at Women & Infants Hospital in Providence, Rhode Island, told Live Science in March that as the drug "becomes more available, patients will ask more questions about its therapeutic value, and, hopefully, more research will be done to answer these questions."
Measles eliminated in the Americas
On Sept. 27, the Pan American Health Organization (part of the United Nations) declared that measles was eliminated from the Americas. Essentially, this means that there are no more cases of measles originating in those countries and that any cases of measles that do arise in those locations come from outside the Americas, Dr. Amesh Adalja, an infectious-disease specialist and a senior associate at the University of Pittsburgh Medical Center's Center for Health Security, told Live Science in September.
"What's keeping measles at bay right now in the Americas is our high vaccination rate," Adalja said. The World Health Organization recommended that countries have at least 80 percent of people living in cities and 95 percent of the entire population vaccinated against measles in order to prevent the spread of imported cases.
New male birth control tested, but rejected
A study on a new, experimental type of male birth control that involves hormone shots was halted early because of the high rate of side effects in men who received the shots. The men's side effects included acne, pain at the injection site, increased sex drive and mood disorders — which garnered attention given their similarity to many side effects of female birth control.
"Although the injections were effective in reducing the rate of pregnancy, the combination of hormones needs to be studied more to consider a good balance between efficacy and safety," said study co-author Dr. Mario Philip Reyes Festin, a medical officer on the human reproduction team at the World Health Organization.
Originally published on Live Science.