Thousands of doses of a potential coronavirus vaccine have been sitting in a Houston, Texas freezer for four years and now officials say it’s time to see if it works.

The vaccine was originally developed to combat severe acute respiratory syndrome or SARS but was literally shelved in a storage facility in 2016 when people lost interest in the disease and funding for human clinical trials dried up.

According to USA Today, as many as 230,000 doses of the vaccine are at a facility called Cryogene in Houston. It was developed based on previous technology that uses yeast, a method that’s used to manufacture hepatitis B vaccines, so it already has a history of safety and efficacy.

“Instead of having to start from ground zero in developing a vaccine, this candidate is virtually ready to go into the clinic. It is very much ahead of the game,” said Deborah Higgins, senior director for vaccine development of PATH, a global nonprofit whose mission is to improve public health. PATH has partnered with Baylor College of Medicine and the Texas Children’s Hospital Center for Vaccine Development to bring the vaccine to human clinical trials.

The rediscovered SARS vaccine, called RBD219N1, works by targeting the cell receptor ACE2, and prevents the virus from latching on to the cell. The vaccine has already been tested in animals and on a laboratory-manufactured virus that closely resembles SARS-CoV-2, the virus that causes COVID-19, says USA Today.

According to the Houston Chronicle, the vaccine, developed by researchers at Baylor College of Medicine and University of Texas Medical Branch at Galveston, effectively protected mice against SARS in earlier trials.