[dgoncharov]

> CAIR2 is specific to California. Every state registry has some technical differences in HL7 V2

Didn't know CAIR2 was only used in CA - I guess a correct statement would be every state has an offshoot of HL7v2, with CAIR2 being one of them, as you mentioned.

> In practice the C-CDAs obtained from providers sometimes include immunization section entries

Yes for sure - we get a lot of those from C-CDAs already, these registries would be just another way to make the data even more authoritative/accurate.