Coronavirus antibody therapies explained

The German government has now announced it will buy 200,000 doses of bamlanivimab and REGN-CoV-2 for a total cost of $485 million, which works out as $2,400 per dose. The drugs will be administered to high-risk patients. Bamlanivimab is a single antibody therapy produced by Eli Lilly. REGN-CoV-2 consists of two antibodies — casirivimab and imdevimab — and has been developed by Regeneron. Former US President Donald Trump was treated with the latter after contracting the coronavirus in October last year. Bamlanivimab and REGN-CoV-2 both received emergency use by the US Food and Drug Administration (FDA) in November 2020. The European Union has yet to greenlight either of the therapies.

Both antibody treatments are designed to block the SARS-CoV-2 spike protein and thus prevent the virus from attaching to and entering human cells. These identical so-called monoclonal antibodies are lab-engineered and designed to attack one specific virus in one distinct way.

Bamlanivimab contains one monoclonal antibody. REGN-CoV-2, in contrast, consists of two monoclonal antibodies. US pharma company Regeneron says its antibody cocktail lowers the viral load, which helps symptoms dissipate more quickly. The advantage of Regeneron’s drug cocktail is that by containing two antibodies, it increases the chance that at least one of them will prove effective during treatment, virologist Sandra Ciesek told German public broadcaster NDR.

Akin to passive immunisations

German Health Minister Jens Spahn has said these treatments “work like passive immunizations,” adding that “administering these antibodies can help at-risk patients avoid a severe case of the disease.”

Vaccinations, however, differ from such monoclonal antibody treatments in that they provoke an immune response in the human body that leads to the production of various antibodies. These bind to the virus in different locations. They are referred to as polyclonal antibodies. In the US, bamlanivimab and REGN-CoV-2 have been approved for treating patients aged 12 years and above who are at risk of developing severe COVID-19 symptoms. The FDA says both treatments reduce the chances of a serious disease progression.

Hospitalized patients, or those reliant on respirators, are not permitted to receive these drugs. REGN-CoV-2 manufacturer Regeneron says people who have not yet produced any antibodies against the coronavirus benefit the most from its antibody cocktail. Treatments proved most effective within 10 days of infection, says FDA head Stephen Hahn. Nevertheless, there is still a dearth of scientific data on this therapy, many scientists say.

German authorities plan to test monoclonal antibody treatments on patients who are either at risk of developing serious COVID-19 symptoms, or who suffer from weak immune systems that do not produce enough antibodies.

-DW