Yes, thanks so much to @lizzy102 and @athenalee for the posts.

Here's a synopsis of CDC findings:

ACIP Data and Clinical Considerations for Additional Doses in immunocompromised patients

"Immunocompromised patients are more likely to get severely ill from COVID-19
 Higher risk for:
*Prolonged SARS-CoV-2 infection and shedding
*Viral evolution during infection and treatment (hospitalized patients)
*Low antibody/neutralization titers to SARS-CoV-2 variants
*More likely to transmit SARS-CoV-2 to household contacts
*More likely to have breakthrough infection:
*44% of hospitalized breakthrough cases are immunocompromised people in US
*40% of hospitalized breakthrough cases are immunocompromised people in Israel"

...rather sobering, and living in Florida in a college town with students beginning classes tomorrow, it's reasonable to think that the situation will become even worse here, before it gets better. I'm pretty much homebound.
I'm 3 yrs out from heart transplant and taking Cyclosporine, Myfortic, low dose pred. Will get a third vaccine soon but can't rely on any response. So fortunate to have my family and my heart 🙂