Amazon is working on a cure for the common cold in a years-long, top secret effort called "Project Gesundheit," according to three people familiar with the effort.

The company has more than 100 working out of Grand Challenge, a research and development group that sits under its cloud division, AWS. A small team in this group, including scientists and technologists, is now working on a treatment for the world's most common illness.

The team is hoping to develop a vaccine, but is exploring a variety of approaches to the problem. Internally, the effort is sometimes referred to as the "vaccine project."

Colds cost the U.S. economy an estimated $40 billion per year, both because of physician visits and lost productivity, according to a landmark 2003 study from the University of Michigan. That number is likely far higher today. That study found that colds, which often last a week, are also responsible for nearly 200 million missed school days, which often mean that parents also have to stay home.

Grand Challenge, which hasn't been publicly acknowledged by Amazon, has a mandate to tackle big problems, ideally finding solutions that will have a major impact on humanity. The group, which has sometimes been known by its code-name "1492," is run by Babak Parviz, who previously worked at Alphabet's research and development effort, then known as Google X. CNBC first reported on the team in 2017.

The hope is that Amazon can build its next big business internally, rather than face disruption by outside forces. Grand Challenge isn't solely focused on health care, but the medical sector has been a major focus from the outset for employees because the market opportunity is so large. Health care is a $3.5 trillion market in the United States alone.

The people familiar with the effort declined to be identified because they're not authorized to speak about internal projects. An Amazon spokesperson declined to comment.