

TLS handles security for the email sent from your device until it reaches the server, and various HIPAA compliance rules mandates security for that data once it reaches that server. It’s not alarmingly less secure than other HIPAA compliant methods of communication, unless the email provider on your end has poor support for TLS emails.
Editing to include the disclaimer that this is for communications sent from your end. For communications sent from their end, this protection doesn’t necessarily apply (it depends on your email provider at that point, which may not be compliant), so for them to send you protected info via e-mail, they usually ask for your consent first, and usually the e-mail is just a link to a portal where you can access that information more securely.
Hasn’t Sabine been getting in some hot water about promoting academic skepticism and making authoritative claims on fields well outside of her expertise?