Gilead generated almost $2bn in revenue from its Covid-19 drug in the fourth quarter, as half of all hospitalised patients in the US are given remdesivir.

The World Health Organization has recommended against the use of Veklury, the drug for Covid-19 also known as remdesivir, arguing that it does not improve survival rates or other outcomes.

But Daniel O’Day, Gilead chief executive, said it had been widely adopted in the US. “Gilead continues to play a central role in the pandemic, with Veklury now treating one in two hospitalised patients in the US,” he said.

The US biotech’s sales soared 26 per cent, beating expectations and pushing shares up 2.3 per cent in after-hours trading in New York.

Veklury sales contributed $1.9bn in the quarter and $2.8bn for the year. It helped make up for falling sales of HIV and hepatitis drugs in the quarter. Product sales in the fourth quarter fell 7 per cent, because of the pandemic disrupting access to healthcare for some patients and the introduction of generic competition to Truvada, an HIV drug, in the US.

The company reported total revenue of $7.4bn, compared with the average analyst estimate of $7.3bn. Non-gaap earnings per share were $2.19, higher than the consensus forecast of $2.15. Net income fell 42 per cent to $1.6bn. Research and development spending rose 20 per cent year on year, driven primarily by investment in Veklury.

The California-based company now expects 2021 product sales, including Veklury, to be between $23.7bn and $25.1bn. For the full year, it expects non-gaap earnings per share of between $6.75 and $7.45.

Andrew Dickinson, chief financial officer, said the forecasts assumed a recovery in the market starting in the second quarter, as vaccination programmes speed up.

“Any delay with a vaccine rollout, or any significant re-acceleration of the global pandemic could once again adversely impact our business,” he said.

But he added that Veklury could act as a “hedge” against the potential impacts of the continued pandemic. Gilead forecast sales of Veklury in 2021 of between $2bn and $3bn, as it also tests new formulations including an oral version of the drug, which is currently an infusion, and in combinations with other medicines.

Gilead said there was no reason to believe that it would not be effective against the new variants of the Sars-Cov-2, as unlike many antibody treatments it does not target the virus’ spike protein, where some mutations have been found.