VACCINE passports could send Covid cases spiking by sending Brits into badly ventilated pubs from larger venues, the Government fears.
Event organisers would have to hire thousands of security staff to check Covid certificates as well as see takings hit by a fall in the number of punters, a leaked report suggests.
The findings are included in analysis marked "official secret" by the Department of Digital, Culture, Media and Sport seen by The Telegraph.
It asked if vaccine passports could have “any displacement effects to other types of venues not included for certification”.
It warned that football fans turned away from stadiums for not having a Covid pass could help fuel the virus by piling into packed pubs to watch games.
The document reads: “There is potential displacement between live events venues and hospitality venues.
"A core concern in the sector is that certification could displace activity and business away from music venues to, say, pubs with music and late alcohol licences, etc. which could be counterintuitive and potentially counter-productive.”
It went on to say: "If certification displaces some fans from structured and well ventilated sports stadia, this could lead to them attending unstructured and poorly ventilated pubs instead, where they will have access to more alcohol than if there were in the stadia.
"Evidence from the Euros showed spikes in cases associated with pubs even when England were playing abroad.”
The impact assessment said an 5,700 stewards would have to be hired at big stadiums so fans could get their Covid certification checked.
It could lead to "bottlenecks" at Premier League games with venues affected suffering a hit of between £345 million and £2.067 billion.
The document says around six million checks would have been needed if the scheme was brought in this month.
Evidence from the Euros showed spikes in cases associated with pubs even when England were playing abroadLeaked document
Vaccine passports would be introduced in some venues under the Government's Plan B to curb a rise in cases over autumn and winter.
The scheme would mean revellers would have to show they'd been double jabbed before going into a venue.
UK daily Covid cases yesterday dropped to 36,567, the lowest figure in two weeks.
If Boris Johnson's plans to keep Covid at bay fails in the coming months, passports will be needed to enter nightclubs, as well as crowded indoor conference halls with more than 500 attendees.
Outdoor settings with more than 4,000 people and sporting and music venues that accommodate over 10,000 will also require an NHS covid pass to enter.
Face masks would also be made compulsory in some settings and people would be asked to work from home again under Plan B for England.
Scotland's vaccine passport scheme was unveiled last weekend but branded an “unmitigated disaster” by the Scottish Hospitality Group.