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A thread on Rapid Antigen testing in community.
All members of Bachhan Household were tested by Rapid Antigen test when Amitabh, Abhishek became http://Symptomatic.Rest were ASymptomatic
All members of Bachhan Household were tested by Rapid Antigen test when Amitabh, Abhishek became http://Symptomatic.Rest were ASymptomatic
Amitabh, Abhishek turned Positive and were taken to Hospital. Aishwarya and her daughter tested negative and RT-PCR was repeated which came out to be positive. Jaya Bachhan tested negative in both. https://english.jagran.com/entertainment/aishwarya-rai-bachchan-aaradhya-coronavirus-swab-test-reports-amitabh-bachchan-abhishek-bachchan-covid19-latest-updates-10013889
Thus False negative rate of Rapid Antigen test in this small sample was 50%.(2/4) ICMR study had informed us that it was between 20-50% ,so it is roughly at lower bound of this range.
However, multiple Recent reports indicate that only Symptomatic Patients who test negative by rapid Antigen test,will be retested by Rt-PCR while ASymptomatic Patients won't be retested by RT-PCR https://theprint.in/health/why-delhis-falling-covid-positivity-rate-may-not-be-good-news-just-yet/449782/
By this strategy, Aishwarya and her Daughter would have been missed. In this recent report in Ghaziabad, where while + rate on Antigen test was only 2.8%(477/16634) the + rate in those who tested negative on Rapid Antigen test was 15% by RT-PCR(263/1666) https://www.hindustantimes.com/cities/from-july-13-confirmatory-rt-pcr-testing-only-for-symptomatic-cases-in-ghaziabad/story-s1CExl6VZcac4V2eMxe3pJ.html
The administration ,alarmed by Rapidly rising rate decided to retest only Symptomatic to decrease their Positivity rate . However we know now upto 30% of COVID patients will never develop Symptoms .
COVID is a disease of indoor and closed/crowded spaces/households spreads maximum to household members. (Attack rate of 10-20%).
Partly the reason temperature and humidity rise in external environment couldn't counter its growth
Partly the reason temperature and humidity rise in external environment couldn't counter its growth
Thus retesting only Symptomatic negative Patients by RT-PCR is a wrong move and Direct/high risk Contacts who are negative on Rapid Antigen test must be retested as they have high probability of Infection as well ,since they can spread it into community at large.
An older thread on how to make upward corrections for Positivity rate while using a combination of Rapid Antigen test and RT-PCR in community for screening. https://twitter.com/anupampom/status/1280041669866344448?s=20
