The Abbott test mentioned above is blood drawn from serum (not a fingerprick blood test!).
This is not the nasal swab test that sometimes misses positive people, as you mentioned.
To avoid confusion over this issue: There is an Abbott nasal swab test, that gives results 15 minutes after being swabbed, and without "special equipment". That specific Abbott test (the instant nasal swab) has experienced dubious results in practice, even compared to more standard nasal swab tests.
This is not the nasal swab test that sometimes misses positive people, as you mentioned.
To avoid confusion over this issue: There is an Abbott nasal swab test, that gives results 15 minutes after being swabbed, and without "special equipment". That specific Abbott test (the instant nasal swab) has experienced dubious results in practice, even compared to more standard nasal swab tests.