@growlingflea, @juggernautsei,
Your code would be very useful in providing Comprehensive COVID-19 Immunization Administration Setup. Do either or both of you have plans for PR?
If CA requires soap envelop around HL7 data and MD accepts pure HL7 batch, chances are other registries will have other combinations. The covid agreement is not that clear if records need to flow thru the state registry to CDC or feed directly into their system. It may be good to store HL7 batches in documents or such folder. Then have another process that will manage the send and receive aspect in a robust fashion.