LONDON (AP) — The head of drugmaker AstraZeneca, which is developing a coronavirus vaccine widely expected to be approved by U.K. authorities this week, said Sunday that researchers believe the shot will be effective against a new variant of the virus driving a rapid surge in infections in Britain.

AstraZeneca chief executive Pascal Soriot also told the Sunday Times that researchers developing its vaccine have figured out a "winning formula" making the jab as effective as rival candidates.

Some have raised concern that the AstraZeneca vaccine, which is being developed with Oxford University, m...