Brexit: What will happen in Northern Ireland?

The European Union (EU) was severely criticised after it said it would introduce controls on coronavirus vaccines moving between the Republic of Ireland (which is in the EU) and Northern Ireland (which is not).

This would have meant overriding part of the Brexit deal on Northern Ireland but the EU decided not to go ahead with the move.

As part of a hard-won peace deal between Ireland and the UK - known as the Good Friday agreement - both governments agreed that the border between Ireland and Northern Ireland should be practically invisible - no cameras, no border posts. This was easy when both were part of the EU, and people and goods could move freely between the two countries.

The UK's withdrawal from the EU meant that a new arrangement was needed because of the risk of checks on goods, creating a "hard border".

The EU has very strict rules about what goods can enter its territory and normally requires goods to be inspected at the point of entry.

After years of negotiations, the EU and the UK set out the new rules in an agreement called the Northern Ireland Protocol which came into force on 1 January 2021.

Under the new deal, checks will not take place at the border between Northern Ireland and the Republic of Ireland.

Northern Ireland continues to follow many of the EU's rules, meaning that lorries can continue to drive across the border without having to be inspected.

However, there will be a new "regulatory" border between Northern Ireland and Great Britain (England, Scotland and Wales). That's because, unlike Northern Ireland, Great Britain no longer has to follow EU law.

This means some checks on goods moving between Great Britain and Northern Ireland will be needed. Some have said this amounts to a border in the Irish Sea.

The EU is facing supply problems with the AstraZeneca coronavirus vaccine.

In response, it announced on 29 January that it would introduce export controls on vaccines produced in the EU. It said this would include vaccines moving between the Republic of Ireland and Northern Ireland.

This could - in theory - have led to new checks along the border in order to prevent EU-produced vaccines from being shipped to the UK.

The EU implemented the measure under Article 16 of the Northern Ireland Protocol which allows either the EU or UK to suspend any part of the agreement that causes "economic, societal or environmental difficulties".

But this sparked widespread concern, including from Irish Prime Minister Micheál Martin as well as all five parties in Northern Ireland's devolved government.

The EU soon reversed its decision. After discussing the matter with Prime Minister Boris Johnson, European Commission President Ursula von der Leyen tweeted that the UK and EU had, "agreed on the principle that there should not be restrictions on the export of vaccines by companies where they are fulfilling contractual responsibilities".

The EU has very strict rules about what can enter its market when it comes to some foods such as meat, milk, fish and eggs.

That means some food products arriving in Northern Ireland from England, Scotland or Wales need to be checked to ensure they meet EU standards - they will need to go through a border control post at sea ports, where paperwork will be checked and some physical inspections will take place.

However, in order to reduce any potential disruption, supermarkets have been given an initial three-month "grace period" where the rules will not be enforced on the food they bring into Northern Ireland. This is to give them time to adapt to the changes and to ensure supplies are maintained.

Some meat products, like sausages, have a longer six-month grace period.

What happens after this period is unclear, and will be the subject of future negotiations.

As well as new physical checks, there are also new paperwork requirements for businesses.

The Northern Ireland Protocol will be reviewed in the future. After four years, the UK is required to give Northern Ireland a vote on whether to continue with the trade arrangements.