Prime Minister Boris Johnson will lead a Downing Street press conference on coronavirus this afternoon.

The press conference will take place at 5pm and the Prime Minister will be joined by chief medical officer Professor Chris Whitty and MHRA chief executive Dr June Raine, No 10 said.

It comes amid concerns over vaccine delays as 1.75 million doses of the AstraZeneca jab are being retested and held in India. 

The head of the Serum Institute of India (SII), which manufactures the vaccine, suggested the country’s government was blocking exports to the UK.

Here are four things Mr Johnson could discuss later today:

Vaccine delays 

Concerns about vaccine supply have been surfacing for a short while, with leaked letters from the NHS warning of a slow down in the arrival of supplies.

Health Secretary Matt Hancock discussed vaccine delays earlier today in the Commons.

He confirmed that no booked appointments would be cancelled and added that second doses of the vaccine can simply not be delayed as they must be delivered within 12 weeks of the first dose. 

However, 1.75 million doses of the AstraZeneca vaccine are currently being held in India for retesting, although there is speculation that this is due to the Indian government temporarily blocking shipments to the UK. 

He said: “Events like this are to be expected in a manufacturing endeavour of this complexity and this shows the rigour of our safety checks.”

A key factor of the easing of lockdown is the successful deployment of the vaccine programme. 

You can expect the Prime Minister to pick this up at the briefing.

AstraZeneca side effects

After reports of dangerous blood clots in some recipients, 10 European nations have paused the vaccine's rollout, including Germany, France, Italy, Spain and the Netherlands.

 This has caused alarm across the nation and is something the Prime Minister and Professor Chris Witty are expected to address this evening. 

The easing of lockdown restrictions

The 'stay at home' order is expected to change to 'stay local' at the end of the month, in just under two weeks. 

As part of step one, there will be further limited changes from 29 March, the week in which most schools will break up for Easter.

Outdoor gatherings of either 6 people or 2 households will be allowed, providing greater flexibility for families to see each other. This includes in private gardens.

Outdoor sports facilities, such as tennis and basketball courts, will be allowed to reopen, and people can take part in formally organised outdoor sports.

At this point, the Stay at Home order will end, although many lockdown restrictions will remain.

This can be expected to be addressed in tonight's briefing. 

Infection rates

As we work out way through the roadmap and out of lockdown there will be a minimum of five weeks between each step - four weeks for the data to reflect changes in restrictions which is then followed by seven days’ notice of the restrictions to be eased.

One of the key tests to the easing of restrictions is Covid infection rates - these cannot increase and must not risk a surge in hospitalisations which would put unsustainable pressure on the NHS.

Matt Hancock said earlier today: "There are 7,218 people in hospital with Covid across the UK – down from a peak of almost 40,000 just seven weeks ago.

“The rate of hospitalisation has halved in just 16 days. And thankfully the rate at which people are dying has fallen by a third in the last week.”

Mr Johnson is likely to provide an update on the latest rates and the number of deaths in the UK.