But professor Stephen Paris warned it would take many months to vaccinate everybody who urgently needs protection.

Batches of the vaccine have started to arrive at hospitals.

Around 800,000 doses are expected to be available across the UK this coming week, with jabs starting on Tuesday.

Our science editor, David Shankman, reports on unmarked van at Croydon University Hospital in south London with a delivery that could start to change the course of the pandemic.

Inside these boxes, the first vaccines for covert 19 ingenious research is creating light of the end of the tunnel.

This is just so exciting.

It's a momentous occasion.

The NHS has been planning extensively for to deliver the largest vaccination program in our history, so it's really exciting.

The vaccines have to be stored at minus 70.

Only large hospitals could do that, so distribution is complicated on will take time.

NHS staff around the country have been working tirelessly to make sure that we are prepared to commence vaccination on Tuesday.

Uh, this feels like the beginning of the end.

But of course it's a marathon, not a sprint, and it will take many months for us to vaccinate everybody who needs vaccination.

So far, only the fighter by on tech vaccine has been approved in the U.

K.

So it's the one that's being used first.

The rollout of this vaccine will involve an operation on an extraordinary scale.

There are something like 6.7 million people judged to be the highest priority residents of care homes, for example, on the over eighties.

So that requires 13.4 million doses.

Because everybody has toe have to now, it's hoped that there'll be 800 0 available in the coming week or so, with up to five million by the end of the year.

But however this pans out, it's going to be a huge challenge.

Production is slower than hoped that fighters plant in Belgium after problems with raw materials.

But other vaccines may come on stream soon, like the one by Oxford University and AstraZeneca now awaiting approval.

Okay, so scratch.

The key factor in all of this is the readiness of the public to get vaccinated.

The medicines regulator wants to reassure people.

I would really like to emphasize that the highest standards of scrutiny of safety and of effectiveness and quality have been met international standards, and so this should be really confidence in the rigor of our approval.

So we're on the brink of the first big step out of the crisis.

But there's a long way to go.