The US government earmarked 10's of billions of dollars for testing. This was a great move!
But why isn't this money being used to make frequent rapid testing more available to the consumer?
Testing is a public health good.
1/x
The government should follow the same successful playbook for frequent testing as it has for vaccines: pay for the tests themselves (as it did for the vaccine) or buy down the price at retail (as it does for the administration for the vaccine itself).
2/x
Why is this important?
1. Children still aren't vaccinated 2. Healthcare workers and others who are vaccinated can still contract the virus (and may be able to pass it on) 3. Less than 50% of US adult population is fully vaccinated
Testing is our eyes to see this virus
3/x
Paying for the tests is a common sense public health strategy to get us through the remainder of this pandemic, using money that is already available.
With 10's of billions of $$ set aside already - the average person should only have to pay a couple dollars a test.
4/x
If we keep costs of these crucial public health tools at $24, this adds to the gross inequities in access to public health.
I'd like to see the US gov work w the test companies to figure out how to get the costs down to <$5 per test in the US. It's the right thing to do.
5/
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Following recovery from COVID19, people remain PCR positive for weeks. These ppl do not transmit virus and needn’t isolate **even if only first tested w PCR after recovery
PCR is not specific for the transmission period nor for requiring isolation
This simple fact - that lab based PCR is not specific to what matters most in a pandemic - whether someone needs to isolate - has been entirely missed in this pandemic and unfortunately at the expense of tests that are fast, accessible AND specific to the infectious period
2/
I hope regulatory / public health agencies understand that public health is not the same as medicine, and the tests needed for public health are different and must meet entirely different metrics to be effective.
I want to clarify this 👆is a very nice and well written article by @TomChivers - pertaining to conventional one-off testing
Frequent accessible testing is however different & repeated use of one or more tests must be factored in to sens/spec calculations & Bayes probabilities
Since false pos are of concern bc they mean ppl isolate when they do not need to, then w that definition @TomChivers it would be interesting if you follow up w a piece on the VERY high false pos PCR rate bc many/most PCR positives are detected AFTER the isolation window passed
This is why we must offer confirmatory rapid tests along w any rapid test program
If we give ppl 20 of test A, we need to give 1-2 of test B - a confirmatory test to use immediately if a pos shows up on A. Can be Ag or Molecular, at home test.
Many rapid tests have False positive rates of 1 in 1000 or less. This is great. But when using huge numbers to control spread, it’s better to have that number at 1 in 10,000 or lower. A simple test A +B if A is positive algorithm would vastly improve specificity.
2/
If we fail to consider a simple addition of a relatively small number of accessible, rapid confirmatory tests, the population may lose confidence. Like all the testing problems, there are simple solutions. We should run with them. Rapid confirmatory tests is one of those.
3/
qPCR is highly specific as a medical test to appropriately identify SARS-CoV2 RNA....
but qPCR is terribly NOT specific as a public health test to determine who should still be isolating (though looking at Ct values can help)
This is not good for public health.
2/
We never should have made qOCR the gold standard for evaluating public health tests. It was a mistake from the beginning bc as CDC readily says - you stay positive on a qPCR test for weeks after you are done transmitting. The specificity is terrible as a public health tool
3/
We know that frequent accessible testing with rapid results can be a critically important tool to slow transmission, keep R<1 and prevent surging cases. Why? because anyone can be exposed to the virus and not realize it until after they have become infectious.
2/x
I hope this new initiative will demonstrate the effectiveness of accessible, frequent at-home rapid testing and subsequently inform national policy to make at-home rapid testing available to all Americans without a prescription (and ideally for free!)
3/x
Population-wide Rapid testing over a two week period of time (Rapid Ag testing of ~50% of population each weekend for two weekends in a row) PLUS subsequent quarantines led to ~70% reduction in prevalence.
Figure above shows the relative reduction in prevalence that occurred - which was consistently substantial across the regions where the population wide rapid testing was performed. Centering around 58%. Compared to what would have happened, the effect was even greater (70%)
2/x
The authors used mathematical models to help understand if the effect noted was due solely to tests, solely to the isolation and quarantines imposed or to both.
They found very strong evidence that it was the overall program - the rapid testing PLUS the behavioral changes
3/x