Making Covid-19 passports mandatory in Britain could reduce cases and deaths from the coronavirus by as much as 40 per cent, former British prime minister Tony Blair's think tank has said.
Mr Blair's Institute for Global Change said the digital pass should be required for entry to nightclubs, indoor performances and sports events.
Britain's National Health Service pass allows people to show they have been fully vaccinated or have a recent negative test result.
Ministers say they are “encouraging and supporting” the use of the app in high-risk settings as nearly all restrictions are lifted in England from today.
But the pass is not compulsory, and critics say it is burdensome for venues and unfair to unvaccinated people.
Mr Blair’s institute said the app should become mandatory while cases are at a six-month high, fuelled by the rise of the Delta variant.
Modelling published by the institute suggested that the use of the pass could prevent between a quarter and a third of projected cases.
On top of that, making the pass compulsory could encourage a higher level of vaccine uptake, potentially leading to a 40 per cent cut in cases.
“With full freedoms restored for pass holders, it is likely this would encourage some vaccine-hesitant people, especially among younger demographics, to have the jab,” researchers said.
Mr Blair has long argued for vaccine passports and called on the UK to take the lead in developing a global health certificate.
About 88 per cent of adults in Britain have received at least one dose of a vaccine. More than 68 per cent are fully vaccinated.
Unvaccinated people can use the app by showing they have taken a PCR or lateral flow test in the previous 48 hours.
Alternatively, people who recently recovered from the virus can provide evidence of a positive PCR test within the previous six months.
The number of deaths in England could be 6,000 to 12,000 lower if the app were to be made compulsory, the institute's modelling suggested.
Such a policy would “restore confidence in hospitality [and] avoid creating super-spreader events and settings,” researchers said.
A similar policy in France, where certificates will become compulsory for restaurants and cinemas later this year, led to more than 100 protest marches at the weekend.
Researchers said that a requirement to use the app in Britain could be dropped once infection rates are lower.
English nightclubs opened on Monday for the first time since the first Covid restrictions were introduced in the spring of 2020.
All capacity limits at sporting events have been lifted, meaning that stadiums could be full again for the start of football’s Premier League season in August.
The government hopes that the Covid pass will become a travel document for British holidaymakers as restrictions on foreign trips are also eased.
Vaccinated people no longer need to go into quarantine when returning from countries on England’s amber list, unless that country is France.
Also being lifted on Monday are mask requirements, compulsory social distancing measures and limits on the size of social gatherings.
But ministers are urging people to be cautious with their new freedoms and say they expect people to continue wearing masks in high-risk places.
“In indoor, crowded places, the right thing to do is wear a mask, and it’s recommended,” vaccines minister Nadhim Zahawi told Sky News.