AstraZeneca's COVID-19 vaccine is not perfect, but will have a big impact on the pandemic, its chief executive predicted, as the drugmaker pledged to double supplies by April.
The two-dose shot, developed with Oxford University, has been hailed as a "vaccine for the world" because it is cheaper and easier to distribute than some rivals.
But its rapid approval in Europe and elsewhere has been clouded by doubts over its most effective dosage and interval between doses.
Data at the weekend also showed it was less effective against a fast-spreading South African variant of the virus, and the company has been embroiled in a row with the European Union over supply delays.
"Is it perfect? No, it's not perfect, but it's great. Who else is making 100 million doses in February?" CEO Pascal Soriot said on a conference call about the vaccine.
"We're going to save thousands of lives and that's why we come to work everyday."
AstraZeneca said it expected much-anticipated data from the US trial of the vaccine before the end of March, and that it was confident the shot offered relatively good protection against severe disease and death for the South African variant. Its disappointing results were against milder cases.
However, after rising to become Britain's most valuable company last summer, the company has now slipped to sixth, in a move some analysts attribute to doubts over the vaccine.
"In a year or two we will look back and everybody will realise we made a big impact," Soriot said.