The health secretary also revealed the Scottish Government is considering plans to replace its vaccine appointment scheme with an online booking system for under-40s, after it emerged that many people given appointments for the jag are not turning up as the roll-out extends to younger age groups.
Mr Yousaf said the system, which had a security glitch that meant people may have been able to edit and fake their Covid vaccine status, had been ditched. The letters were created in case people needed to prove their status if travelling abroad.
Speaking in response to a question in Holyrood on Wednesday from Liberal Democrat leader Willie Rennie, Mr Yousaf said the glitch, which was identified a few days ago, meant the government had stopped the programme.
"Upon learning of the security glitch to download the vaccination status letter, that option has been disabled,” Mr Yousaf said.
"Requests for free-of-charge vaccination status records can be made from the freephone Covid-19 vaccination status helpline.
"As the Covid status certification programme progresses, the letter will be replaced by a digital Covid status certificate, which is likely to include their vaccination status and negative testing data.”
Mr Yousaf added: “No decision has been taken on using Covid status certificates domestically. However, I do have ethical clinical and quality concerns about their use and am going to host their own table with human rights and equality experts to discuss these very issues.”
Mr Rennie said: “When I asked the First Minister about vaccine passports last year, she said she did not favour them. Without even a debate in Parliament or a public consultation, the government is pressing ahead.
"There is no clarity on how these will work, what they will be used for and for how long. It seems like the government is making it up as it goes along.
“It took five minutes for a junior researcher to identify a major security flaw in the vaccination status letter. The public deserves to know whether the system has been properly tested. We cannot expect foreign government to trust it if we don’t.”
Mr Yousaf said the status letters were part of people’s medical records and did not constitute a vaccine passport. He said that no decisions on the issue had been made and would ideally be carried out as a four-nations approach.
Labour MSP Pauline McNeill asked about the situation in Glasgow, where it emerged that at the weekend, 83 per cent of people did not turn up for vaccine appointments at the Hydro mass vaccination centre.
She suggested that a bookings appointment scheme, which has already been set up for under-30s, should be extended to all ages.
Mr Yousaf said: “I can tell Ms McNeill that urgently after the statistics we saw this weekend, I'm talking to the team about using the online portal for 18 to 20-year-olds and are looking to see whether we can extend that to cohort ten – that's those from 40 to 49.”