American pharmaceutical company Eli Lilly and Co said on Tuesday that it has paused the government-sponsored clinical trial of its coronavirus antibody treatment because of a safety concern, reported Reuters.

“Out of an abundance of caution, the ACTIV-3 independent data safety monitoring board (DSMB) has recommended a pause in enrollment,” an Eli Lilly spokesperson told the news agency in an emailed statement. “Lilly is supportive of the decision by the independent DSMB to cautiously ensure the safety of the patients participating in this study.”

The company, however, did not comment on the implications for the paused trial, which compares patients who receive its antibody drug and antiviral drug remdesivir with those receiving only the latter.

A United States National Institutes of Health spokesperson said the trial was paused when the data safety board found that after five days, the group of patients who received the antibodies showed a different “clinical status” than those who received a saline placebo, The New York Times reported. This difference crossed a predetermined threshold for safety, the spokesperson added.

The statement from the National Institutes of Health said the independent safety board will review the data on October 26 and advise the medical research centre if the trial can resume. The researchers would continue to collect data from people already enrolled in the study till a decision is made.

United States President Donald Trump had taken a similar treatment to that of Eli Lilly and said it was equivalent to a Covid-19 cure.

The company had sought an emergency use authorization for the drug from the regulators after it published data in September that showed that the Covid-19 drug reduced hospitalisation and emergency room visits for the infected patients. It was developing the treatment with Canadian biotech firm AbCellera.

The drugmaker is also working on the treatment of coronavirus patients who need hospitalisation. it is also testing a drug in nursing homes to ascertain if it can prevent the Covid-19 infection among staff and residents.

The decision to halt the clinical trial follows Johnson & Johnson’s announcement on Monday that it has temporarily paused the advanced clinical trial of its experimental Covid-19 vaccine because of an unexplained illness in one of the volunteers.

Last month, pharmaceutical company AstraZeneca had also paused late-stage trials of its experimental coronavirus vaccine after a study participant developed an unexplained illness. However, four days later on September 12, the company resumed the clinical trials in the United Kingdom after getting the approval from the health regulatory authority.

The United States has so far reported 78,56,605 Covid-19 cases and its toll stood at 2,15,887, according to John Hopkins University.