AstraZeneca chief executive Pascal Soriot said on Sunday that the British pharmaceutical company’s vaccine is believed to be effective against the new coronavirus strain detected in the U.K.

“So far, we think the vaccine should remain effective. But we can’t be sure, so we’re going to test that,” Soriot said when asked how the vaccine could hold up against the new variant of the virus.

The Associated Press reports Soriot told the Sunday Times that researchers for AstraZeneca had discovered a “winning formula” to make its formula just as effective as Pfizer’s or Moderna’s, both of which have already been approved. The AstraZeneca vaccine is expected to be approved this week, the AP notes.

“We think we have figured out the winning formula and how to get efficacy that, after two doses, is up there with everybody else,” Soriot said.

AstraZeneca’s vaccine, developed in partnership with Oxford University, was not initially believed to be as effective as its American counterparts, with partial results suggesting it is 70 percent effective at preventing illness, the AP reports.

This new strain of the virus has elicited alarm across the globe, with many countries limiting or banning travel from the U.K. The variant is believed to be significantly more contagious than the pre-existing coronavirus strain, though it not believed to be more deadly or cause more severe symptoms.