The pharmaceutical giant Johnson & Johnson has agreed to share all of its clinical trial data with the Yale Open Data Access Project (YODA), an unprecedented agreement that will provide researchers across the globe with a trove of information about drug development and disease.

The agreement, reached January 6 after negotiations spanning the past 16 months, marks the first time a pharmaceutical company has relinquished decision-making authority over which of its data can be accessed by outside parties. YODA was founded two and a half years ago to facilitate open access to pharmaceutical clinical trial data, but its one previous agreement — with the medical device company Medtronic — only stipulated that the company share data on one drug. Now, researchers say, the agreement will allow the biomedical community to answer questions for which data was not previously accessible.

“This is a landmark decision,” said Harlan Krumholz ’80, a professor of cardiology at the Yale School of Medicine, who directs YODA. “They’re saying that all of their data is ultimately available to scientists around the world. No matter what country you’re in, no matter who you are, if you have a question and you want to get access to the data, you’ll be able to do it.”

According to Joseph Ross MHS ’06, a YODA co-principal investigator, Johnson & Johnson chose to partner with Yale because the University is the only one with an open access data project dedicated specifically to clinical trial data.

Ross said although pharmaceutical companies conduct many large clinical trials every year, around half of those trials are never published, and the public cannot gain access to the results. Unless a company is trying to gain FDA approval for a drug, in which case it is legally required to submit the clinical trial data to the agency, the company is not compelled to show anyone its results, he said.

But with the agreement, only revealing the data for FDA approval is no longer the standard for Johnson & Johnson, which produces common drugs including Benadryl, Motrin, Sudafed and Tylenol. Now, researchers can request data through an online form to further explore the study’s original questions or engage in new ones.

In clinical medicine, assembling large numbers of research subjects for trials is difficult, time-consuming and expensive, Krumholz said. If pharmaceutical companies are not publishing the results of these studies, no one can benefit from the immense resources put in, and researchers may even have to duplicate these studies because they cannot access existing results, he added.

“[Open access] is about maximizing the value of the human subjects’ time and the sponsors’ investment in the data,” Ross said.

But even with the increased efficiency in scientific research that open access brings, pharmaceutical companies have not been eager to share their data, said Robert Alpern, dean of the Yale School of Medicine. Such companies often claim that their competitors want access to their study data, and if a company has spent a lot of money to generate the results, it does not want its competitors to have it for free, he said.

Even if pharmaceutical companies are hesitant to share data, Alpern said they understand that doing so can help their public images, some of which have been tarnished by drug recalls. In September 2004, for instance, the pharmaceutical company Merck withdrew the painkiller Vioxx over concerns that it increased risk of heart attack. Krumholz said had researchers had access to the clinical trial data, they could have discovered the drug’s impact on the heart.

Open access will also facilitate more varied interpretations of clinical trial results, Krumholz said. Because published studies are only one interpretation of the raw data, the agreement will bring in more voices to analyze the results, he said.

In 2013, Johnson & Johnson was ranked 41st of the Fortune 500 companies in revenue, generating $67.2 billion.

Correction: Feb. 23

A previous version of this article stated that the agreement between Johnson & Johnson and YODA had been reached on the week of January 26th. In fact, the agreement was announced last week, but was completed on January 6th.