AstraZeneca says its COVID-19 drug cuts the risk of severe disease in half. It's the first antibody cocktail shown to both prevent and treat the disease in late-stage trials.

• AstraZeneca said its antibody drug cut the risk of severe COVID-19 in half in a late-stage study.
• The drug, called AZD7442, is a combination of two antibodies given as an injection.

AstraZeneca's antibody drug cut the risk of severe COVID-19 by at least 50% in a late stage study, the company announced on Monday.

The injection, called AZD7442, contains two different antibodies developed from the the blood of people who previously contracted COVID-19. It's the first drug of its kind shown to both prevent and treat COVID-19 in late-stage trials, the company said in a press release.

The company has already requested Food and Drug Administration (FDA) approval to use AZD7442 to prevent COVID-19, after late-stage trial results in August showed it reduced the risk of COVID-19 with symptoms by 77%.

It would now discuss the latest data with health authorities, it said.

The results come after Merck, the US pharmaceutical company, said on Monday it would ask the FDA to authorize its oral COVID-19 pill, which halved the risk of hospitalization or death in a trial.

The latest AstraZeneca results, from the TACKLE trial, showed that the risk of severe COVID-19 or death was halved if people took the drug within seven days of COVID-19 symptoms, AstraZeneca said. Out of 407 people who got the drug, 18 developed severe COVID-19 or died - compared with 37 of 415 people who got a saline injection.

If AZD7442 was given earlier, within five days of symptoms, the risk of severe COVID-19 was reduced by 67%, the company said. On this timing, nine of 253 participants in the AZD7442 group got severe COVID-19 or died, compared with 27 out of 251 in the placebo group.

AstraZeneca tested the drug on 822 adults with mild to moderate COVID-19 in 13 countries, including the US and UK, it said. The drug, which works by stopping the virus that causes COVID-19 from binding to the body's cells, was "generally well tolerated," it said in the release. It didn't detail any side effects.

Protection for vulnerable people

Mene Pangalos, executive vice president at AstraZeneca, said in a statement that "early intervention with our antibody can give a significant reduction in progression to severe disease, with continued protection for more than six months."

AstraZeneca looked at the drug's impact at day 29 of the TACKLE study, which is expected to follow participants for up to 15 months. AstraZeneca's early stage studies have previously shown that antibodies last at least nine months after the drug is given.

Penny Ward, visiting professor in pharmaceutical medicine at Kings College, London, said in a statement that long lasting protection, up to 12 months, may be "a useful addition for immune-suppressed individuals whose response to vaccination is suboptimal."

Most people in the trial, 90%, had comorbidities that put them at high risk of severe COVID-19, including cancer, diabetes, obesity, chronic lung disease or asthma, cardiovascular disease, or immunosuppression, and 13% were aged over 65, AstraZeneca said.

Ward said that unlike oral pills, monoclonal antibody treatments given as an injection, such as AstraZeneca's, don't interfere with other medicines. This "may potentially make administration simpler for these patients," she said.