Gilead sold $873 million worth of its antiviral COVID-19 treatment even though data on its success remains mixed

• Gilead posted its first numbers detailing how much money the pharmaceutical company has made through Veklury, a COVID-19 antiviral treatment.
• Gilead sold $873 million worth of Veklury, also known as remdesivir, in three months.
• The FDA authorized Veklury as the first antiviral treatment approved to treat COVID-19 patients.
• Studies on the effectiveness of Veklury present mixed results. The World Health Organization tested Veklury on more than 2,750 COVID-19 patients and found the antiviral drug Remdesivir had "little or no effect" on survival.

Pharmaceutical firm Gilead is raking in millions from Veklury, an FDA-approved antiviral treatment to COVID-19.

Gilead sold $873 million worth of Veklury, otherwise known as remdesivir, in July, August, and September. The Food and Drug Administration granted emergency use for the drug in May.

The FDA later granted authorization for Veklury in all uses in October. Veklury is the only FDA-approved antiviral drug to treat COVID-19 patients.

Veklury helped give Gilead a 17% year-over-year increase in revenue, amounting in $6.6 billion. Of the total Veklury sales, US buyers generated $785 million while European and others comprised a smaller portion of customers.

Research into Veklury's effectiveness in treating COVID-19 patients remains mixed. The World Health Organization accidentally posted a study of 237 participants that indicated Veklury did not help patients with severe coronavirus cases. A separate WHO study of more than 2,750 COVID-19 patients suggested that the antiviral drug remdesivir had "little or no effect" on survival.

Read more: Gilead is set to sell billions of dollars of a coronavirus drug that's far from 'amazing' after the US approved remdesivir to treat COVID-19

The National Institutes of Health conducted a placebo-controlled study with 1,000 hospitalized patients and found though Veklury shortened recovery times by five days for participants, taking the drug did not lower the chances of dying.

On a call to investors, Gilead touted the success of the drug. Merdad Parsey, Gilead's chief medical officer, said factors in the WHO's study — including that it had not been peer-reviewed, did not disclose whether patients received a high flow of oxygen, and reported missing data in the preliminary analysis — may have contributed to "negative outcomes."

Parsey said antiviral treatments are most effective during the early stages of a disease.

"I'm extremely grateful that a therapy exists that has been validated with all of the rigor required for an FDA approval," Daniel O'Day, chairman & CEO of Gilead Sciences, said on the call.

Gilead sales of Veklury could total $5.4 billion in 2020 and $8.5 billion in 2021, per SVB Leerink industry analyst Geoffrey Porges. Wall Street projects a more conservative estimate of $2.4 billion for this year and $2.7 billion next year, Business Insider's Andrew Dunn reported.