Sabina Vohra-Miller Profile picture
Dr Public Health candidate | MSc Pharmacology/Toxicology | Vohra Miller Foundation w @craigmillr | Unambiguous Science | First Exposure | South Asian Health Nw

May 8, 2024, 7 tweets

New post on Rapid Antigen Tests. Will post the entire thread here instead of just a link, given importance.

A master thread with current data: key concepts, which brands are more sensitive, tips to improve sensitivity & important considerations. 1/7

Recent CDC MMRW Report found overall sensitivity of RATs was 47% compared to PCR.
The peak percentage of positive RAT was 59.0% occurred 3 days after onset of symptoms.
Highest on days when fever was reported, lowest on days when no symptoms were reported. 2/7

Overall QuickVue and Flowflex had the highest sensitivity. Special mention for Australian Fanttest. Several commonly used RATs performed extremely poorly.
3/7

One study showed RAT accuracy increased from 38% to 92% with repeat testing.
A single negative RAT test cannot rule out infection.
Current guidance suggests to repeat the test 48 hours after the first negative test & potentially a 3rd time if you still have symptoms. 4/7

Including an oral sample along with a nasal sample on the same swab can increase test sensitivity.
5/7

If you are elderly, at higher risk, eligible for anti-virals such as Paxlovid, PCR tests are recommended.
If your RAT is positive, you continue to be infectious.
To know when to stop isolating or masking, two consecutive -ve RATs 24 hours apart (after a +ve RAT). 6/7

A post on key concepts and considerations 7/7

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