(Reuters) – The U.S. National Institutes of Health (NIH) has started a late-stage trial to evaluate if immune-modulating therapies from three drugmakers can help reduce the need for ventilators for COVID-19 patients and shorten their hospital stay.

The NIH said on Friday it has selected three agents for the study – Johnson & Johnson unit Janssen Research’s Remicade, Bristol Myers Squibb’s Orencia and Abbvie Inc’s experimental drug cenicriviroc.

The study will enroll up to 2,100 hospitalized adults with moderate to severe COVID-19 symptoms in the United States and Latin America.

Immune-modulating therapies are medications that alter the way the immune system works. Severe infections are believed to be triggered by an over-reaction of the immune system, known as a “cytokine storm,” and drugs that suppress certain elements of the immune system can play a role in arresting a rapid escalation of symptoms.

This can lead to acute respiratory distress syndrome and multiple organ failure, among other life-threatening complications.

The NIH said its clinical trial – ACTIV-1 Immune Modulators (IM) – will last six months, and the agency will study if the therapeutics can restore balance by modulating that immune response.

All patients will be given Gilead Sciences Inc’s antiviral drug remdesivir – the current standard of care – and also be randomly assigned to receive a placebo or one of the immune modulators as an add-on treatment, the NIH said in a statement.

Remdesivir was one of the drugs used to treat U.S. President Donald Trump’s coronavirus infection, and has been shown in previous studies to have cut time to recovery, though the European Union is investigating it for possible kidney injury.

(Reporting by Vishwadha Chander in Bengaluru, Editing by Sherry Jacob-Phillips)