The writer is director of competition policy at the International Center for Law and Economics

There is a good chance that the UK’s 2021 is a lot like Australia and New Zealand’s 2020. With vaccinations running at a decent speed, and assuming the Johnson & Johnson and Novavax jabs are also approved, the UK should be able to vaccinate most of the at-risk population against coronavirus by the middle of the spring.

But other countries are much further behind on vaccinations, so there is a danger of a vaccine-resistant variant emerging abroad. If it makes its way to the UK, that could bring us back to stage one, where the virus could again only be controlled by a return to lockdowns.

In the long term, the UK can deal with this by expanding its ability to manufacture newly developed mRNA vaccines, which can be redesigned in days to deal with new strains. But until then, the government should control international travel, just as Australia, New Zealand and Taiwan did after eliminating their initial outbreaks. This could allow life to return to relative normality at home, at the cost of strictly quarantining international travellers.

Apart from the challenge of cross-Channel freight, one big problem with this plan is that the UK is not one island. It shares a 310-mile border with the Republic of Ireland that cannot be easily shut. The countries have had a Common Travel Area since Irish independence. This allows passport-free travel between Ireland and the UK, and until the pandemic it had only been suspended once, during the second world war. The EU last week briefly banned vaccines from crossing that border, but not people. Even that provoked uproar and was swiftly abandoned.

Although the Isle of Man and the Channel Islands are also in the CTA, and have closed their borders to most inbound travel during Covid-19, shutting the border between Ireland and the UK entirely would be much harder, since many people travel between the Irish Republic and Northern Ireland on a daily basis. Quarantining internal travel within the UK — between Northern Ireland and Great Britain — would probably be politically impossible.

If a vaccine-resistant variant of Covid entered Ireland from overseas and took hold there, it could spread to the UK. Apart from the difficulty of restricting entry, if Ireland has another big outbreak before it has vaccinated much of its population, it may be difficult to detect new variants. A border closure may be too late before we even realise it is necessary.

This creates a serious risk. While the UK has vaccinated about 14 per cent of people so far, Ireland has only managed about 3 per cent, largely because of the EU’s disastrous vaccine-procurement plan. It seems likely that Ireland will continue to lag behind the UK.

Because of this, the UK government should consider offering vaccines to the Irish Republic, and setting up a joint policy on quarantining visitors from third countries. Vaccines could be shared once all over-50s and other at-risk people in the UK who want a vaccine have been given one, hopefully allowing Ireland to catch up rapidly. Since Ireland’s population is less than 5m, this could be done quite quickly, without significantly slowing the UK’s progress towards full herd immunity.

Once the virus had been suppressed through vaccine and infection-based immunity in both countries, they could return to relative normality. Free movement between Britain and Ireland could be maintained, and the risk of a vaccine-resistant variant entering would be mitigated with quarantine rules agreed on a mutual “two island” basis. This would emulate the Australia and New Zealand travel bubble, which has allowed travel between them without quarantine. That was temporarily suspended after a case of the 501.v2 variant first identified in South Africa was confirmed in New Zealand, but has now been reopened. We would still have to be vigilant about new outbreaks.

This Common Immunity Area would have benefits for the UK beyond pandemic management. It would allow the British government to act generously towards Ireland after a difficult five years since the Brexit vote. It would also be a stark contrast to the EU’s current, shameful vaccine nationalism, demonstrating that the UK aimed to take the high road and help its neighbours at a time when the bloc is pursuing beggar-thy-neighbour protectionism.

And it would be a comfort to the approximately 380,000 Irish-born people living in Britain, and 100,000 UK nationals in Ireland. Many have not seen families back home since March. Provided they could do so safely, it would be a great relief. I should declare an interest: I am one of them.