Costa Rica’s equine plasma coronavirus treatment not as effective as initially hoped

Treating coronavirus patients with an antibody-rich serum made from horse plasma hasn’t produced the desired results, Costa Rican authorities said.

Román Macaya, executive president of the Costa Rica Social Security System (CCSS), said at a Wednesday press conference that the clinical studies of the serum showed minimal impacts on patients with COVID-19.

“Equine serum was implemented to see its safety and efficacy to neutralize the effects of the virus. It was found to be well-tolerated by patients, but the efficacy is not as desired,” Macaya said, according to La Nación.

“It was not slowing the progression of the disease or the development of complications.”

Macaya, who didn’t provide further details on the findings, said health authorities will continue clinical studies using different dosages.

When the equine serum treatment was first announced, Macaya hoped it would reduce the average length of the average COVID-19 hospitalization, helping to free Costa Rica’s limited hospital capacity.

The Clodomiro Picado Institute at the University of Costa Rica — which specializes in snake antivenoms — created the serums from the blood of horses that were injected with non-infectious SARS-CoV-2 proteins.

The serum was shown to inhibit the infectivity of SARS-CoV-2, the virus that causes COVID-19, during in vitro tests performed at the National Center for Biodefense and Infectious Diseases in the United States. In vitro refers to a study performed outside of a living organism. 

The treatment was not meant as a replacement for an eventual vaccine.

The Clodomiro Picado Institute began exploring equine plasma to treat COVID-19 in April.