Last week the FDA granted Abbott Labs an Emergency Use Authorization for their BinaxNOW antigen test. The test costs $5 (materials only) and reads out in 15 minutes, with a 1.5% false positive rate and 2.9% false negative.
The BinaxNOW lateral-flow immunoassay requires only a nasal swab — just inside the nostril — not the deep nasopharyngeal swab we are accustomed to hearing about in the RT-PCR test. Its collection will be far less uncomfortable. (A note on SARS-CoV-2 testing collection: In TWiV 658, Daniel Griffin [“America’s Clinician”] revealed that the amount of virus collected on a nasal swab is about a factor of 8 less than for the deeper collection point. The virus in saliva should be at about the same level as for nasopharyngeal collection.)
This is not a home test. The FDA requires it to be administered in a point-of-care setting by a trained technician (who, granted, would need less exacting training than nasopharyngeal collection requires), and only to patients who are exhibiting symptoms. In other words, in keeping with the FDA’s overall philosophy (and reason for existing), this is a diagnostic test to benefit one individual; it is not and cannot be used as a screening test to benefit all of society.Abbott’s test has much to recommend it as an adjunct to, perhaps almost a replacement for, the gold-standard RT-PCR test. It is far faster: you get an answer in minutes instead of days. It is more acceptable to patients due to the less invasive nasal collection. And it costs much less.
But it is not the cheap-frequent-quick test described by Michael Mina — the screening test we need to bring this pandemic rapidly under control. A Mina test, detecting the contagious phase of a SARS-CoV-2 infection, will be administered at home, by ordinary people not technicians, and will cost at most $1 all-in.
It will also need to be made available on a scale orders of magnitude greater even than Abbott’s ambitious plans. Abbott says it will ship 10 million tests in September and by the end of that month ramp up production to 50 million kits per month. Mina testing would require 200 times that many tests: a billion per month in order to test the entire US population daily. No one company can do this. It’s going to require all hands on deck — that is, after the FDA admits a role for testing that is not diagnostically focused.