LONDON (Reuters) - The prospect of a vaccine in the first quarter of 2021 gives reason for optimism that the spring will be better, British Prime Minister Boris Johnson said on Saturday, after he announced a new national lockdown for England until December. “I am optimistic that this will feel very different and better by the spring. It’s not just that we have ever better medicines and therapies, and the realistic hope of a vaccine in the first quarter of next year,” Johnson said at a news conference. “We now have the immediate prospect of using many millions of cheap, reliable, and above all, rapid turnaround tests... that you can use yourself to tell you whether or not you’re infectious and get the result within 10 to 15 minutes.”