Gilead Sciences Inc GILD.O on Wednesday cut its 2020 revenue forecast, citing lower-than-expected demand and difficulty in predicting sales of remdesivir, the only treatment approved in the United States for patients hospitalized with COVID-19. Remdesivir brought in $873 million in the quarter, below analysts’ estimates of $960 million, according to Refinitiv IBES data. Gilead Chief Commercial Officer Johanna Mercier said that although the United States saw a surge in COVID-19 cases over the summer, many were younger people and hospitalization rates actually dropped. “Our assumption is in light of the surge this fall both in Europe and the U.S., those numbers will pop back up,” she said. Gilead lowered the top end of its full-year sales outlook to $23.5 billion, which is below Wall Street estimates of $24.1 billion. The company had previously forecast 2020 sales as high as $25 billion. “The revision in guidance is tied, not entirely, but almost entirely to expectations around Veklury,” Gilead Chief Financial Officer Andrew Dickinson said, using the brand name for remdesivir. “There was less demand in the third quarter than expected.” Remdesivir is authorized or approved for use in more than 50 other countries around the world. It was one of the treatments given to U.S. President Donald Trump during his recent bout with COVID-19. Gilead said some sales recorded in the third quarter are being held in inventory for use in the fourth quarter, and the volume of remdesivir purchased for government stockpiling purposes fell short of what the company had projected. Remdesivir has become the standard of care for patients hospitalized with severe COVID-19, but many U.S. doctors remain wary of using it in patients with less severe illness. “There is still uncertainty about the pandemic and still lingering questions about the visibility of remdesivir with antibodies coming,” Jefferies analyst Michael Yee said, referring to experimental antibody drugs designed to treat COVID-19. Gilead shares, which closed down 2%, fell another 1.5% in extended trading. Third-quarter revenue of $6.6 billion beat the average analysts’ estimate of $6.31 billion. The company posted adjusted earnings per share of $2.11, topping Wall Street expectations by 21 cents. Sales of the company’s flagship HIV drugs rose 8% from a year earlier to $4.55 billion, as patient demand normalized following disruption related to the pandemic. Remdesivir was granted emergency use authorization by the U.S. Food and Drug Administration in May after it was shown to shorten hospital stays for COVID-19 patients in a government-run clinical trial. Commercial sales began in July and the FDA formally approved the drug this month, despite recent results from a World Health Organization-sponsored trial showing remdesivir did not improve patient outcomes.