People who have had both jabs will be able to use the NHS app as a vaccine passport for overseas travel from Monday.
Those who do not use smartphones can phone 119 for a paper letter confirming their vaccine status but have been urged not to ask their GP.
The government hopes the app will be able to show vaccination status in time for people to be able to use it when the ban on foreign travel is lifted on May 17.
The app will not show Covid test results but it is hoped that they will be incorporated by the time domestic Covid status certification is due to be introduced for mass events on June 21.
The NHS app was set up to allow people to book appointments and repeat prescriptions online and allows people to see their full medical records.
NHS Digital, the health service’s technology unit, has been working on tweaking the app so that vaccine data is pulled out of medical records and shown on a separate screen that can be presented to officials, The Times reported.
People must register to use the app and the government is advising people to do so at least two weeks before they travel abroad. As an alternative they can apply for a paper letter but this is available only five days after the second dose and will take a further five days to arrive.
The government website says: “From May 17, you may be able to show your Covid-19 vaccination status as proof of your status when travelling abroad to some countries or territories.
“You can access your Covid-19 vaccination status through the free NHS App from May 17. You can access the app through mobile devices such as a smartphone or by tablet. Proof of your Covid-19 vaccination status will be shown within the NHS App. We recommend you register with the app before booking international travel.”
It adds: “Demonstrating your Covid-19 vaccination status allows you to show others that you’ve had a full course of the Covid-19 vaccine when travelling abroad to some countries or territories. A full course is currently two doses of any approved vaccine.”
However, it says: “There are not many countries that currently accept proof of vaccination. So for the time being most people will still need to follow other rules when travelling abroad – like getting a negative pre-departure test.”
The advice adds: “If you do not have access to a smartphone and know that the country you are travelling to requires Covid-19 vaccination status, you can call the NHS helpline on 119 from 17 May and ask for a letter to be posted to you. This must be at least 5 days after you’ve completed your course of the vaccine. We expect the letter to take up to 5 days to reach you.
“Do not contact your GP surgery about your Covid-19 vaccination status. GPs cannot provide letters showing your Covid-19 vaccination status.”