Rob Stein

Updated at 8:25 p.m. ET

Federal health officials issued a blunt message Tuesday: Americans need to start preparing now for the possibility that more aggressive, disruptive measures might be needed to stop the spread of the new coronavirus in the U.S.

The strongly worded warning came in response to outbreaks of the virus outside China, including in Iran, Japan, South Korea and Italy, which officials say have raised the likelihood of outbreaks occurring stateside.

Updated at 6:34 p.m. ET

A second person in the United States has been infected with a dangerous new coronavirus that is spreading in China, U.S. health officials announced Friday.

A woman in her 60s got infected with the virus while traveling in the Wuhan, China, area in late December and became ill after returning home to Chicago Jan. 13, according to officials from the federal Centers for Disease Control and Prevention and the Illinois and Chicago health departments.

Researchers have conducted a controversial study that involved paying dozens of young women at a hospital near Puerto Vallarta, Mexico, to get artificially inseminated so their embryos could be flushed out of their bodies and analyzed for research purposes.

The study showed that embryos created that way appear to be as healthy genetically as embryos created through standard in vitro fertilization. Physically, the embryos appear to, possibly, even be healthier, the study found.

When Victoria Gray was just 3 months old, her family discovered something was terribly wrong.

"My grandma was giving me a bath, and I was crying. So they took me to the emergency room to get me checked out," Gray says. "That's when they found out that I was having my first crisis."

Doctors are reporting the first evidence that genetically edited cells could offer a safe way to treat sickle cell disease, a devastating, incurable disorder that afflicts millions of people around the world.

Billions of cells that were genetically modified with the powerful gene-editing technique called CRISPR have started working, as doctors had hoped, inside the body of the first sickle cell patient to receive the experimental treatment, according to highly anticipated data released Tuesday.

The powerful gene-editing technique known as CRISPR has raised a lot of hope in recent years for its potential to offer new ways to treat many diseases, including cancer. But until now, scientists have released very little information about results of tests in patients.

On Wednesday, researchers revealed data from the first study involving U.S. cancer patients who received cells genetically modified with CRISPR.

Scientists have created a new way to edit DNA that appears to make it even easier to precisely and safely re-write genes.

The new technique, called prime editing, is designed to overcome some of the limitations of CRISPR. That technique, often described as a kind of molecular scissors for genes, has been revolutionizing scientific research by letting scientists alter DNA.

Victoria Gray slides open a closet door, pulls out a suitcase and starts packing piles of clothes.

"My goodness," says Gray. "Did I really bring all this?"

Gray, who has sickle cell disease, is the first patient with a genetic disorder whom doctors in the United States have tried to treat using the powerful gene-editing technique CRISPR.

There's been a lot of excitement lately that the powerful gene-editing technique CRISPR could offer a new way to treat health problems ranging from cancer to blindness.

But there hasn't been much direct scientific evidence in actual patients about whether it might work or would be safe — until now.

Chinese scientists have published the first report in a scientific journal of an attempt to use CRISPR-edited cells in a patient--a 27-year-old man who is HIV-positive.