Interestingly, that STAT article has a comment at the bottom referencing this study in Denmark (of LTCF residents (long term care facility residents, median age 84) and HCWs (health care workers, median age 47)):
That study found that the Pfizer / BioNTech vaccine was not that effective after first dose + two weeks (0% in LTCF residents and 17% in HCWs). After two doses + one week, effectiveness was 90% in the HCWs but only 64% in the LTCF residents.
The lower effectiveness in the LTCF residents is not a big surprise (older age and general poor health tend to correlate with worse immune system functioning – it also means that vaccinating the staff and visitors is also important), but the one dose low effectiveness in HCWs seems contradictory to the study finding 80% effectiveness after one dose.