CAIR2 is specific to California. Every state registry has some technical differences in HL7 V2 Messaging support but most are reasonably close to the CDC/AIRA spec.
> 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.
https://repository.immregistries.org/resource/hl7-version-2-...
The CDC IZ Gateway can make it somewhat easier to work with multiple state registries.
https://www.cdc.gov/vaccines/programs/iis/iz-gateway/overvie...
In practice the C-CDAs obtained from providers sometimes include immunization section entries so you can pick up some records that way as well