Boris Johnson stresses need for caution over Pfizer vaccine

Boris Johnson has welcomed news of the Pfizer coronavirus vaccine but has urged caution. Speaking during a Downing Street press conference, the Prime Minister said the news was a sign the "scientific cavalry" was on its way, but stressed "these are very, very early days". "The biggest mistake we could make now" he said, "would be to slacken our resolve at a critical moment." .