Nov 23 (Reuters) - The top U.S. infectious disease medical association said on Monday that Gilead Sciences Inc's antiviral drug remdesivir should be used for hospitalized COVID-19 patients despite a World Health Organization (WHO) recommendation last week against its use.

The Infectious Diseases Society of America (IDSA) in updated guidelines said its experts back the drug for use in severe COVID-19 patients based on a clinical trial showing it reduced hospital stays. The WHO study that led to its recommendation against the drug suggested it had no benefit in saving lives or reducing the need for mechanical breathing assistance.

"As hospitals around the United States fill up, the IDSA panel views the effect of remdesivir speeding up time to recovery to be an important benefit," Dr. Rajesh Gandhi, co-chair of the society's COVID-19 treatment and management guidelines expert panel, said on a call with reporters. "Better medicines that improve survival are clearly needed."

Unlike the trial that led to its U.S. regulatory approval, the WHO's study was not placebo-controlled. Studies with a placebo comparison are generally considered more scientifically rigorous than those without a control group.

The IDSA also has advised against the routine use of Eli Lilly and Co's COVID-19 antibody treatment bamlanivimab, which received U.S. emergency use authorization. The IDSA panel said it recommended against its routine use for ambulatory patients, but that it may still be appropriate for patients with increased risks after a discussion with their doctor.

"Antibodies may end up having a role. I think we just need more definitive data," Dr. Gandhi said. "I want to keep our eye on what benefit they may end up having as well as which patients are most likely to benefit."

It said Roche Holdings Ag's rheumatoid arthritis drug Actemra, known chemically as tocilizumab, is not recommended for routine use in hospitalized COVID-19 patients, saying there was still not enough evidence supporting its benefits. (Reporting by Rebecca Spalding Editing by Bill Berkrot)