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Number one comment of concern I receive about why we can& #39;t deploy rapid daily #COVID19 tests that test for people with likely transmissible virus:
"We can& #39;t do this yet because we don& #39;t know the exact cutoff viral load for transmissibility"
This misses the point...
1/n
"We can& #39;t do this yet because we don& #39;t know the exact cutoff viral load for transmissibility"
This misses the point...
1/n
We KNOW that transmission occurs when viral loads are high
We know people are likely transmissible a couple days prior, to ~1 week after symptom onset. And we know during this time, virus is often MUCH HIGHER (10,000x - 1,000,000,000x) than the limit of detection of PCR)..
2/n
We know people are likely transmissible a couple days prior, to ~1 week after symptom onset. And we know during this time, virus is often MUCH HIGHER (10,000x - 1,000,000,000x) than the limit of detection of PCR)..
2/n
So we don& #39;t need to wait for human transmission experiments (won& #39;t happen) to solve this.
We know enough to know what will help. And a test that detects within 1000x the limit of detection of PCR will be more than sufficient to detect most people who are transmitting.
3/n
We know enough to know what will help. And a test that detects within 1000x the limit of detection of PCR will be more than sufficient to detect most people who are transmitting.
3/n
We can& #39;t allow imperfect knowledge slow us and prevent us from fixing a massive problem that is right now killing hundreds of thousands of people
We know enough- we don& #39;t need an exact cutoff and, frankly, there will not be an exact cutoff. Transmission is much more complex
4/4
We know enough- we don& #39;t need an exact cutoff and, frankly, there will not be an exact cutoff. Transmission is much more complex
4/4
Final thought - Even IF some ppl can transmit when viral load is <1000x the limit of PCR, getting daily tests to millions of ppl that can detect >1000x the limit will catch MOST people when infectious. Public health tests don& #39;t need to be perfect to stop raging outbreaks.
They just need to break enough transmission chains to bring R way below one. And all evidence suggests that a daily test for everyone that tells people exactly when to isolate would do this very quickly. These are transmission blocking tests. Not diagnostic and not perfect.
