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Getting very tired of people misusing my threads on testing to try and state that PCR is crap and LFDs are amazing.
Both tests have limitations.
PCR is still the gold standard for diagnostics.
Let's clear it up in simple language so that my words cannot be misused anymore.
Both tests have limitations.
PCR is still the gold standard for diagnostics.
Let's clear it up in simple language so that my words cannot be misused anymore.
LFDs are relatively cheap, scaleable, and give results rapidly. They are less sensitive than PCR, and so less likely to detect residual positives.
These are the good things.
However, LFDs will miss *a lot* of infectious cases. This is *very* bad.
These are the good things.
However, LFDs will miss *a lot* of infectious cases. This is *very* bad.
rRT-PCR (PCR) is highly sensitive, meaning if you're infectious at the time of the swab, its v likely to detect you.
This is v good.
However, results can take >48h to get back, & if doing asymptomatic testing, PCR will detect some non-infectious residual positives.
This is bad.
This is v good.
However, results can take >48h to get back, & if doing asymptomatic testing, PCR will detect some non-infectious residual positives.
This is bad.
There is also the problem that both tests are unlikely to detect cases who are early in the incubation period (who have a low viral load), although PCR will still detect these cases before LFDs.
The point here is, as with everything in the pandemic, there is no magic solution.
The point here is, as with everything in the pandemic, there is no magic solution.
Testing is very complex, particularly asymptomatic and at this scale. Cases will always be missed, and this is the main concern. Data from ongoing pilot studies will tell us more, and we must await the publication of this before rolling new tests out on a large scale.
Once the data is published, we then have to make decisions, taking all things into account, including cost-effectiveness, behavioural concerns, and system level effects.
Science can guide us, but there are no good options. Only less bad options.
Science can guide us, but there are no good options. Only less bad options.
People claiming PCR is bad are wrong. People claiming LFDs are perfect are lying.
People claiming there are simple solutions to testing, or anything in the pandemic, are either massively uninformed or, you guessed it, lying.
People claiming there are simple solutions to testing, or anything in the pandemic, are either massively uninformed or, you guessed it, lying.
I find it sad that I try & go to great lengths to include nuance, balance, give a full picture & educate on testing, but like 10 times a day now people just select the words they want to hear & form a narrative. :(
Very frustrating.
Very frustrating.
I hope the hysteria around testing ends soon and I can go back to focusing on my research interests and not have to listen to people who have never set foot in a lab in their life chat about cycle thresholds as if they have one iota what they are actually talking about.
