The trial will assess the drug’s ability to prevent infection among those who have had close contact to an infected person, such as a patient’s housemate

Specifically the release noted that a Phase 3 trial of the drug will assess its ability to prevent coronavirus infection among uninfected people who have had close contact to an infected person, such as a patient’s housemate. The Phase 3 prevention trial is happening at around 100 sites and expected to include 2,000 patients across the United States, according to Regeneron.

The drug also has moved into the Phase 2/3 portion of two trials testing its ability to treat hospitalized and non-hospitalized patients with Covid-19, according to Regeneron. These trials will involve 1,850 hospitalized patients and 1,050 non-hospitalized patients, and they are expected to be conducted at 150 sites in the United States, Brazil, Mexico and Chile.

“We are running simultaneous adaptive trials in order to move as quickly as possible to provide a potential solution to prevent and treat COVID-19 infections, even in the midst of an ongoing global pandemic,” Dr. George D. Yancopoulos, co-founder, president and chief scientific officer of Regeneron, said in the company’s news release.

The release also noted that the trial is being run jointly with the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.

Antibodies are proteins the body naturally makes to protect the body from a threat like Covid-19. To make what’s called monoclonal antibodies for an antibody cocktail, scientists comb through thousands of antibodies to figure out which ones fight the novel coronavirus most effectively.

In this case, Regeneron’s scientists picked two antibodies, scaled them up and put them into a medicine that it hopes can be used to treat symptoms and possibly even work as protection for vulnerable communities such as the elderly or health care workers.

Entering these late-stage trials means that the drug already has shown positive results in earlier trials in humans assessing safety, which began in June. The Phase 1 safety results included an initial cohort of 30 hospitalized and non-hospitalized patients with Covid-19, according to Regeneron.

Regeneron said last month that its antibody cocktail will be tested in four separate study populations: people who are hospitalized with Covid-19; people who have symptoms for the disease, but are not hospitalized; people who are healthy but are at a high risk for getting sick; and healthy people who have come into close contact with a person who is sick.

Regeneron is not the first company to get a Covid-19 antibody therapy into human trials. Eli Lilly and AbCellera started testing their antibody treatment in humans June 1. There are a handful of other companies working on additional antibody therapies.

CNN’s Jen Christensen contributed to this report.