Could mixing different Covid vaccines provide as good - or even better - protection than two shots of the same drug? That's exactly what a UK trial aims to find out, with more than 800 volunteers over the age of 50 in England to be given the Oxford-AstraZeneca jab followed by the Pfizer-BioNTech vaccine - or vice versa - four or 12 weeks apart. Other vaccines may be added as they are approved by regulators.
The aim is to provide more flexibility with the vaccine rollout and help deal with any potential disruption to supplies. Scientists have reason to believe mixing vaccines may prove beneficial. Some Ebola immunisation programmes mix different jabs to improve protection, for example. Those not taking part in the trial will receive their second dose of the same vaccine from the same place, as planned, over the expected 12-week interval.
Here's what you need to know about the various vaccines.

There has been another twist in the case of Anne Sacoolas, who's accused of killing motorcyclist Harry Dunn in a crash near RAF Croughton, Northants, in 2019. She had returned to the US, claiming diplomatic immunity, before a Home Office request to extradite her was refused. Now there are suggestions she was working for US intelligence. When asked why Mrs Sacoolas had "fled" the UK, her barrister told a US court: "I know the answer but I cannot disclose it." He was asking a judge to dismiss a Dunn family claim for damages. Afterwards, a family spokesman said: "Given the admission in open court by Mrs Sacoolas's counsel that she was employed by US intelligence services at the time of the crash, the UK authorities must now urgently reinvestigate whether she had diplomatic immunity."

A climate scientist is warning Boris Johnson he risks "humiliation" when hosting a UN climate summit this year if he fails to stop the creation of a new coal mine in Cumbria. In a letter, former Nasa researcher James Hansen tells the PM he can "change the course of our climate trajectory" at the Glasgow conference or "stick with business-almost-as-usual and be vilified around the world". No 10 says the UK is cutting carbon emissions faster than any major economy and will end the use of coal for electricity by 2025 but it will not reverse councillors' approval of the Whitehaven mine.

There's a tone of optimism in this morning's papers, with the Metro among the papers quoting government scientists saying "we're past the peak" of the coronavirus pandemic. The i focuses on the UK's vaccination "milestone", its headline reading simply: "10 million." And many front pages capture what the Daily Mirror calls a "nation's thank you" to Capt Sir Tom Moore who died, aged 100, months after raising £33m for NHS charities.

After hearing how round-the-world sailor Pip Hare was a big fan, actor Russell Crowe sent a surprise birthday message to help her "keep going" to the end of the gruelling Vendee Globe race. Watch it here (though it might make you feel a little seasick).

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