Hey there NeedlepointShop,
Thanks for reaching out to the Apple Support Communities.
To get started, the only ways to add vaccination information to the Health app would be by using a QR code, or downloading a file received by your healthcare provider.
For more details, check out this link here: Download health records on iPhone - Apple Support
You can use a QR code or a link from a healthcare provider or authority to download a verifiable COVID-19 vaccination or test result record, and you can set up automatic downloads for a range of health records from supporting healthcare organizations.
We hope that's able to help answer your questions.
Best regards.