LONDON (AP) — AstraZeneca said Thursday it expects to have a new version of its COVID-19 vaccine ready for use by this autumn as drugmakers respond to concerns about emerging variants of the disease that may be more transmissible or resistant to existing vaccines.

The Anglo-Swedish company, which makes a vaccine developed by the University of Oxford, said it is working with the university's scientists to adapt the shot to combat new variants. Researchers began this work months ago when the variants were first detected, said Mene Pangalos, head of biopharmaceuticals research for AstraZeneca.

"We're moving fast and we've got a number of variant versions in the works that we will be picking from as we move into the clinic," Pangalos said on a conference call with reporters.

The comments came as CEO Pascal Soriot defended the company's efforts to develop and ramp up production of the shot amid criticism from the European Union and a preliminary study that raised concerns about the vaccine's ability to combat a variant of COVID-19 first discovered in South Africa.

While rollout of the vaccine hasn't been perfect, regulators in a number of countries have found the vaccine to be safe and effective, and AstraZeneca will produce 100 million doses this month, Soriot said. Only a handful of vaccines have been authorized for widespread use out of hundreds that began development a year ago, he noted.

"One hundred million doses in February means 100 million vaccinations, which means hundreds of thousands of severe infections that are avoided, and it also means thousands of deaths that are avoided," Soriot said.

The EU last month sparred with AstraZeneca after the company cut initial deliveries of the vaccine to the bloc because of production problems.

Although the European Medicines Agency approved the AstraZeneca vaccine for use by everyone over 18, some European countries, including France and Germany, have recommended that people over 65 not receive the shot due to limited data on its effectiveness in older people.

Just this week, researchers released preliminary results from a small-scale study in South Africa that found that the vaccine did little to prevent mild to moderate cases of the disease caused by the variant prevalent in the country. The study also looked solely at healthy young people.

But Soriot stressed that the vaccine is very good at preventing severe disease and death, which is the most important goal.

"We could get lost in a lot of details about this and that, but you have to look at the big picture," Soriot said. "And the big picture is today we have a vaccine that has been approved by several important regulators, all these scientific questions have been adjudicated by the regulators. … This month we're going to manufacture 100 million doses, in April 200 million doses."

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