It depends and not all Public Health Labs will do all of these:
Send HL7 V2 messages of many flavors to providers’ EHR systems
have web portals that allow download of pdf documents
send secure emails with pdf documents or link to the webportal
All still do this to some extent:
fax or mail results
In urgent cases they will call the provider
Trinity Health exchanges data using all three listed, plus fax and at least two proprietary exchange platforms that allow exchange with offices lacking an EHR but having internet-accessed drop-boxes.