The drug, bamlanivimab, is authorized for COVID-19 patients who are 12 years of age and older weighing at least 40 kilograms, and who are at high risk for progressing to severe COVID-19 and (or) hospitalization, according to a statement of the FDA on Monday.

This includes those who are 65 years of age or older, or who have certain chronic medical conditions.

Monoclonal antibodies are laboratory-made proteins that mimic the immune system's ability to fight off harmful antigens such as viruses. Bamlanivimab is a monoclonal antibody that is specifically directed against the spike protein of SARS-CoV-2, designed to block the virus' attachment and entry into human cells.

While the safety and effectiveness of this investigational therapy continues to be evaluated, bamlanivimab was shown in clinical trials to reduce COVID-19-related hospitalization or emergency room (ER) visits in patients at high risk for disease progression within 28 days after treatment when compared to placebo, said the FDA.

The data supporting the EUA for bamlanivimab are based on an interim analysis from a phase two randomized, double-blind, placebo-controlled clinical trial in 465 non-hospitalized adults with mild to moderate COVID-19 symptoms.

Of these patients, 101 received a 700-milligram dose of bamlanivimab, 107 received a 2,800-milligram dose, 101 received a 7,000-milligram dose and 156 received a placebo within three days of obtaining the clinical sample for the first positive SARS-CoV-2 viral test.

For patients at high risk for disease progression, hospitalizations and emergency room (ER) visits occurred in 3 percent of bamlanivimab-treated patients on average compared to 10 percent in placebo-treated patients.

The effects on viral load and on reduction in hospitalizations and ER visits, and on safety, were similar in patients receiving any of the three bamlanivimab doses, according to the FDA.

The EUA allows for bamlanivimab to be distributed and administered as a single dose intravenously by health care providers.

"The FDA's emergency authorization of bamlanivimab provides health care professionals on the frontline of this pandemic with another potential tool in treating COVID-19 patients," said Patrizia Cavazzoni, acting director of the FDA's Center for Drug Evaluation and Research. "We will continue to evaluate new data on the safety and efficacy of bamlanivimab as they become available."

Based on review of the totality of the scientific evidence available, the FDA determined that it is reasonable to believe that bamlanivimab may be effective in treating non-hospitalized patients with mild or moderate COVID-19. And, when used to treat COVID-19 for the authorized population, the known and potential benefits outweigh the known and potential risks for the drug, according to the FDA.

Possible side effects of bamlanivimab include anaphylaxis and infusion-related reactions, nausea, diarrhea, dizziness, headache, itching and vomiting, according to the agency.

The EUA came as the United States surpassed 10 million COVID-19 cases Monday, just 10 days after hitting 9 million. The recent average number of daily new infections has exceeded 100,000, and public health experts have warned that the country is entering the pandemic's worst phase. Enditem