There is one document you cannot show from your phone: the International Certificate of Vaccination, the WHO’s yellow booklet. In 2026 it is still paper, still a legal document, and at some borders it still decides whether you get in.
When it is genuinely demanded
The clear case is yellow fever: dozens of countries in Africa and South America require the certificate if you arrive from an endemic area — and some, like Tanzania or Kenya with a layover, check it at the desk. Saudi Arabia requires ACWY meningitis for Umrah and Hajj. Other stamps (oral cholera, polio on certain routes) depend on the year and the outbreak. The list moves — which is why a serious travel plan is checked against the alerts of the month you travel, not against a 2019 PDF.
What makes a stamp valid
A stamp holds if three things accompany it: the date, the exact batch of the vaccine given, and the signature with licence number of the person who gave it. Without a batch there is no traceability; without a signature, nobody accountable. It is the same reason a Medora nurse records the batch in your file at the moment of the injection: if a border doubts your booklet six years from now, the record exists and someone answers for it.
How we do it at home
You book the service, a doctor reviews your destination and history within 24 h, and a nurse comes up to your home with the clinical cooler: cold chain from pharmacy to arm, vaccines given, and the record stamped on the spot, in your living room, valid at any border. If several of you travel, it is all stamped in one visit — children included, who are grateful to skip the queue at an international vaccination centre.
The stamp takes a minute. What makes it worth something is everything recorded behind it.