Recent rules and guidance changes have breathed new life into the UK's travel industry after months of stagnation caused by Covid-19.
Almost all testing requirements were abolished for fully vaccinated travellers returning to England from a non red-list country after October 4.
Just three days later, the UK government slashed the numbers of countries on its red list from 54 to seven, effectively approving unlimited travel to all parts of the globe.
The UK's travel rules unspooling was complemented by a change of government guidance against journeying to 32 countries, some of which had not been on the red list even before its reduction.
In light of the new "old" normal, the Tony Blair Institute has produced the Keeping Travel Open: a Vaccine Anywhere, a Vaccine Everywhere report in which it outlines a strategy for keeping the international travel moving. These are its three key precepts.
1. Recognise all WHO-approved vaccines
Although the UK's amber list was nominally abolished on October 4, it remains in all but name for the countries not on the UK's approved list of vaccine providers.
Passengers with a valid vaccination certificate from the countries and territories on the scheme will be treated as if they had been immunised in the UK and can follow the rules for fully inoculated travellers.
The original list of countries caused some confusion by including Saudi Arabia and Qatar, but not the UAE.
It proved to be an aberration that was swiftly resolved and the UAE was added to the 17 countries and territories approved to administer vaccines outside Europe and the US by a public health body.
The report says the situation could have been avoided by the UK aligning its approved vaccine providers scheme with that of the World Health Organisation, the embodiment of "international best practice".
In this scenario, the country of inoculation becomes an irrelevance as long as the vaccine is approved by the WHO.
There are seven WHO-approved vaccines, those produced by Moderna, Johnson & Johnson, Oxford-AstraZeneca, Pfizer/BioNTech, Sinovac, Sinopharm and the Serum Institute of India.
2. Resolve global vaccine certification issues
If the UK fails to adopt this approach, the report suggests it should provide other countries with a "fair and transparent set of criteria on what constitutes acceptable certification".
It calls on the government to adopt a standardised, tech-driven model for certification, which it says could make the UK a travel policy bellwether.
The report also says that any measures to expand vaccine recognition must be concomitant with "enhanced measures to prevent fraud".
The G20 is proposed as a crucible for a common certification policy aimed at limiting the scope for forgeries.
Vaccine issues are not just bureaucratic, according to the report, expressing concerns over the "quality of vaccine administration".
It calls for a sensitive acknowledgement of these concerns and says the problem should not be conflated with that of vaccine certification.
"Countries should also be provided with a transparent assessment of exactly what needs to be improved for them to be recognised as an approved provider," the report says.
3. Remove UK red list as soon as feasible
Ever since the UK unveiled its travel red list, the criteria it uses to determine which countries should be on it has been a hot topic of debate.
There are no clear criteria or hard thresholds for what constitutes a red-list country.
The decision is left to the discretion of government ministers on the basis of qualitative and quantitative data presented to them by the Joint Biosecurity Centre.
The report says that the JBC is right to avoid hard-and-fast thresholds for red-list countries, but calls for the data on which the decisions are based to be made widely available.
It says this would help to "demystify an opaque process and ensure that ministers can be held to account".
Beyond greater transparency, the report says the UK red list must not be allowed to become a "forever" solution.
To pave the way for a red-free world, it calls for more frequent reviews teamed with clear benchmarks, those of the EU’s safe list, and suggests the UK move towards an EU or US-style travel policy where entry is based on vaccination status, not country of origin.
"The UK must recognise that the red list alone will never stamp out variants of concern, and it must act decisively to promote genomic-sequencing efforts and help vaccination campaigns abroad," the report says.