Drug trials on coronavirus patients in China yielded mixed results, with an HIV pill showing little benefit and a flu medication made by Fujifilm Holdings Corp. resulting in faster clearance of the virus.

The combination of lopinavir and ritonavir, marketed by AbbVie Inc. as Kaletra, didn't improve the condition of severe COVID-19 patients or prevent them from dying more than standard care in a randomized, controlled trial of 199 patients. The research was published Wednesday in the New England Journal of Medicine.

A separate study of 80 patients receiving Fujifilm's favipiravir, or Avigan, found it helped clear the virus from patients a week earlier than the HIV medicine and was associated with improved chest symptoms shown on CT scans.

The favipiravir study, which wasn't randomized, was conducted in a different group of patients and at a later time point when doctors might have discovered better ways to care for patients, Evercore ISI analyst Umer Raffat said in a note.

The clincial research on favipiravir augers well for another anti-viral, Gilead Sciences Inc.'s experimental drug remdesivir, which is also undergoing clinical trials in China, Tyler Van Buren, an analyst with Piper Sandler said. Results of the remdesivir study are yet to be published.

"If successful, it could be approved for broad use in the coming months considering it's safe, the bar for efficacy in the context of the ongoing global pandemic is low," he said.

Patients in the lopinavir and ritonavir trial were also found to show more gastrointestinal side effects such as vomiting and diarrhea than those not given the drug in the comparison group. Nearly 14% of those taking the drug were unable to finish the 14-day therapy, mostly because of the gastrointestinal disorders.