Eli Lilly's COVID-19 antibody halted in 6 more states as Regeneron's competing option sails along

The coronavirus is a moving target. And so it goes with the drugs used to treat it.

Never was that more apparent than on Wednesday.

Within hours of granting emergency use approval to a COVID-19 antibody drug by GlaxoSmithKline and Vir, the United States has restricted the use of another COVID antibody treatment, this one from Eli Lilly.

RELATED: FDA orders COVID antibody makers Regeneron, Eli Lilly to track virus variants

The FDA has halted the distribution of Lilly’s combination of bamlanivimab and etesevimab in Arizona, California, Florida, Indiana, Oregon and Washington––all states where coronavirus variants from Brazil and South Africa account for more than 10% of those with the disease. The antibody combo had previously been paused in Illinois and Massachusetts. 

Providers in those states should use Regeneron’s antibody treatment of casirivimab and imdevimab, the FDA says. Lab studies have shown that option is more effective against the Brazilian (P.1) and South African (B.1.351) strains, according to the agency.

For Lilly, it's a continuation of an unfortunate trend. Last month, the FDA halted the use of bamlanivimab alone as a COVID-19 treatment throughout the U.S., citing concerns over its ability to tackle variants. 

RELATED: As variants take hole, FDA revokes authorization of Eli Lilly's solo COVID-19 antibody

The most recent action comes two months after the FDA ordered Lilly and Regeneron to monitor the effectiveness of their antibody cocktails against the South African variant. Both drugs are used in mild-to-moderate COVID-19 patients with a high risk of disease progression.

As part of the directive, the FDA asked both companies to make their findings available on a monthly basis.

Meanwhile, with GSK and Vir's approval on Wednesday, a third entrant has entered the field. It remains to be seen how those companies will roll that drug out, given that they don't yet have a supply deal with the U.S. government.