By Peter Loftus

Eli Lilly & Co. said its antibody-based drug prevented Covid-19 among many residents and staff of nursing homes and assisted-living facilities, results that point to the drug complementing vaccines while inoculations increase.

The drug, called bamlanivimab, reduced the risk of both staff and residents getting sick with Covid-19 by about 57% compared with a placebo, Lilly said Thursday. The effect was more pronounced among residents, the company said, an 80% reduction in risk of Covid-19.

The findings signal the potential for a new preventive weapon that could augment the fledgling Covid-19 vaccination effort to stem the pandemic.

Lilly said it would ask U.S. health regulators to widen the drug's authorized use to include protecting people in long-term-care facilities where someone has recently been diagnosed with Covid-19.

The partial results were from a last-stage, or Phase 3, study conducted in partnership with the National Institutes of Health. Lilly disclosed the data in a news release and said it plans to publish full results in a peer-reviewed medical journal.

In November, the U.S. Food and Drug Administration authorized bamlanivimab to treat people already sick with mild to moderate Covid-19, based on a prior study showing it helped improve symptoms and kept patients out of the hospital.

Lilly Chief Scientific Officer Daniel Skovronsky said it would be useful to give bamlanivimab as a preventive measure because not all long-term-care residents and staff have received the new Covid-19 vaccines.

"We want to try to get this to people in nursing homes," he said in an interview. "It's not an alternative for a vaccine. It's for people who haven't been vaccinated, and there's an outbreak in their facility -- this could be a last resort."

Nursing homes and other senior-care facilities have been hit hard by the coronavirus, accounting for a large percentage of deaths during the pandemic. A Wall Street Journal review found the facilities were tied to a third of Covid-19 deaths world-wide.

Residents are at risk of exposure because of the congregate setting, and of severe disease because most are elderly or have underlying health conditions.

So far, at least 1.9 million Covid-19 vaccine doses have been administered in long-term-care facilities, according to the U.S. Centers for Disease Control and Prevention. It estimates there are about 3 million residents of long-term-care facilities in the U.S., each needing two doses of the new vaccines.

Yet hesitancy among facility staff to receive the shots has slowed the rollout of the vaccines in the facilities, which are being administered by pharmacy chains CVS Corp. and Walgreens Boots Alliance Inc.

Lilly started the 5,000-subject study in August in U.S. nursing homes that had a recently diagnosed case of Covid-19, putting residents and staff at high risk of exposure. The study is ongoing and is also testing combining bamlanivimab with another antibody.

Once a case was diagnosed, other residents and staff were tested for Covid-19 and offered an intravenous infusion of bamlanivimab. For people who tested positive, the study also tracked whether bamlanivimab was effective as a treatment.

The prevention data that Lilly released was from 965 people -- 299 residents and 666 staff -- who had tested negative for the virus at the start of the study.

Among these residents, four people subsequently contracted the disease and died from it, and all had received a placebo. No residents who tested negative and received the Lilly drug died from the disease, Lilly said.

Lilly said side effects of the drug in the new study were consistent with what was seen in prior studies, with small percentages experiencing nausea, dizziness and headache.

The federal government has agreed to purchase about 950,000 doses of Lilly's antibody for about $1.2 billion, and to make the doses free to patients.

The FDA authorized a similar antibody-based treatment from Regeneron Pharmaceuticals Inc., one that had been given to then-President Donald Trump for treatment of Covid-19 in October.

The drugs belong to a class of medicines known as monoclonal antibodies that are designed in labs to mimic the naturally occurring antibodies that the immune system produces to fight off viruses and other foreign invaders.

Lilly developed its drug in collaboration with AbCellera Biologics Inc., of Vancouver, British Columbia, which isolated antibodies from a blood sample taken from one of the first Americans to recover from Covid-19.

Since their authorizations, however, the antibody products haven't been used to treat sick patients as widely as the companies or federal health officials had hoped. Some infectious-disease specialists have cited limited evidence of their effectiveness, while primary-care doctors sometimes aren't aware of the option.

About 454,000 doses of Lilly's antibody have been distributed in the U.S., according to the U.S. Department of Health and Human Services.

Dr. Skovronsky said he hopes the new treatment results from the nursing-home study will give doctors more confidence to use the drug in patients.

Lilly also is developing additional antibody treatments for Covid-19. The company believes bamlanivimab will still be effective against the coronavirus variant that has spread in the U.K., but has less confidence it can work against a different variant identified in South Africa, Dr. Skovronsky said.

Yet he added that Lilly should be able to develop an antibody that would work against the South African variant.

Write to Peter Loftus at peter.loftus@wsj.com

(END) Dow Jones Newswires

01-21-21 0814ET