Interestingly, the Lucira test was 100% sensitive for all samples that had a PCR CT value of < 37.5 (n=45). The CT value is the number of times that the PCR test has to amplify (i.e. make copies of) the genetic material in the sample before there was enough material that it produced a positive test result. A low CT value means that there is a lot of viral RNA present; a high CT value means the opposite.
A CT value of 37.5 is exceptionally high; it corresponds to about 10 copies of virus per microliter. Someone only becomes infectious (it's believed) when the copies per microliter is in the hundreds of thousands. PS don't quote me on the precise numbers here as I am trying to remember them and it's a bit fuzzy.
On the information sheet, they say that, "Lucira achieved a 94% positive percent agreement (PPA) and a 98% negative percent agreement (NPA)."
Positive agreement is the proportion of comparative/reference method positive results in which the test method result is positive.
Negative agreement is the proportion of comparative/reference method negative results in which the test method result is negative.
Interestingly, the Lucira test was 100% sensitive for all samples that had a PCR CT value of < 37.5 (n=45). The CT value is the number of times that the PCR test has to amplify (i.e. make copies of) the genetic material in the sample before there was enough material that it produced a positive test result. A low CT value means that there is a lot of viral RNA present; a high CT value means the opposite.
A CT value of 37.5 is exceptionally high; it corresponds to about 10 copies of virus per microliter. Someone only becomes infectious (it's believed) when the copies per microliter is in the hundreds of thousands. PS don't quote me on the precise numbers here as I am trying to remember them and it's a bit fuzzy.
On the information sheet, they say that, "Lucira achieved a 94% positive percent agreement (PPA) and a 98% negative percent agreement (NPA)."
Positive agreement is the proportion of comparative/reference method positive results in which the test method result is positive.
Negative agreement is the proportion of comparative/reference method negative results in which the test method result is negative.