Holidaymakers could find themselves waiting days to be granted access to their medical records to prove vaccination status for travelling abroad, a doctor has warned.
And it has already-stretched GPs "worried" about the potential extra workload dumped on their laps in the coming weeks.
The NHS app will be ready to be used as a de facto vaccine passport when the borders re-open on Monday for non-essential travel, Transport Secretary Grant Shapps has said.
But there could be a major 'glitch' in the system that will see surgery switchboards clogged up with wannabe jet-setters needing permission for upgrades.
Mark Porter, a GP in Wotton-under-Edge, Gloucestershire, said many people "may not have access to all the information" contained in the NHS app, including inoculation status.
And that's if they've even downloaded it at all.
Are you a GP who is concerned about the NHS app being used as a vaccine passport? Let us know at webnews@mirror.co.uk
It is different to the NHSX-developed Covid app which came out last year and is used for contact tracing.
Rather, the NHS app was launched a couple of years ago to allow patients to request repeat prescriptions, arrange doctors appointments and view medical records.
Writing in a column for The Times yesterday, Dr Porter said: "The whole process takes about five minutes, but there can be up to a week’s delay before you are granted access to your records — another reason to do it now rather than just before you travel.
"Depending on how your electronic record was set up, you may not have access to all the information it contains, including your vaccine status.
"NHS advice is to contact your GP to upgrade your access if required, but if millions of travellers do that our switchboard is going to be even more overwhelmed than it is at the moment."
Dr Porter said it is a stumbling block that is "worrying practices like mine" and if a solution isn't found "upgrading access on an individual basis is simply not feasible given pressures".
The UK government has announced a 'green list' of 12 countries which can be travelled to from May 17 without the need to quarantine for two-weeks on return home.
Among the list are Portugal, Iceland, Israel and Gibraltar, with travel companies seeing a surge in bookings for the former in particular.
Downing Street has also confirmed the NHS app passport would satisfy the entry requirements of multiple countries, including Greece and Spain, which were placed on the amber list, meaning quarantine is required.
Being vaccinated won’t be mandatory everywhere, though each country will still have its own rules, including quarantining on arrival and Covid-19 testing.
Some countries have said you’ll need to be fully-vaccinated before arrival, such as Spain and France.
