In Dispatch 156, I wrote about why it didn’t make sense to use rapid antigen tests all the time, or to rely too much on them, as Delhi is still.
In short, these tests return too many false negative results (identifying an infected person as not infected) to be reliable. And the established protocol (which, to make matters worse, is not strictly followed by anyone) to ensure that symptomatic individuals who test negative on a rapid antigen test are given a molecular test like RT-PCR as a follow-up. It doesn’t make sense: at least 40% and up to 80% of those infected with Sars-CoV-2, the virus that causes coronavirus disease (Covid-19), are asymptomatic.
Sure, there is a context where it makes sense to use rapid antigen tests. After all, they give results in an hour, compared to the 24 hour minimum it takes for an RT-PCR test (and in practice, with logistical delays and delays, this can go up to three or four days at times. ). Therefore, in containment zones, at airports and train stations, and before public events (such as the JEE and NEET entrance exams; no tests were administered to candidates, wasting a great opportunity to test large numbers of people), at any time. it’s a limitation: it makes sense to use rapid antigen tests. And sure, it makes sense to make sure a follow-up RT-PCR test is given to symptomatic people who test negative for antigen.
I previously suggested a trick that could make antigen tests more accurate: two tests administered in parallel to two samples from the same patient (if there is a discrepancy between the two results, a molecular test is administered). This cuts the chances of a false negative in half.
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Lastly, I’ve also written about new rapid antigen tests (one was recently released by Abbott Laboratories, but only in the US), which are fast, inexpensive, and just as accurate as molecular tests. We must get them. At the time of writing the column referred to in the first instance – it also mentioned Uttar Pradesh and Bihar, two other states that relied too heavily on rapid antigen testing – I did not expect that I would have the opportunity to use an example of real life to explain why such Tests should not be used indiscriminately would be presented in a few days. The mathematics presented in that column were simple, but due to the hypothetical situation the administrators of Delhi, Lucknow, and Patna may have overlooked its importance.
And so, with that elaborate prelude, let’s look at Exhibit A: The Delhi Assembly.
Here’s what we know: 50 lawmakers attended the one-day special session of the Delhi assembly on Monday. All had previously undergone RT-PCR testing, but not all results had come in by Monday morning. These legislators were administered a rapid antigen test. It’s not immediately clear how many were tested. It was also administered to the assembly officials and journalists who covered the session. An MLA tested positive and was immediately quarantined. The others tested negative and the session began. The positive RT-PCR results of two MLAs occurred even while the session was in progress – they left the assembly immediately, but by then their colleagues had already been exposed to them. While all 47 tested negative, they have shared a locked room (a large one) with the two lawmakers, ideally they should go into quarantine and get tested after five days (if infected, it will show up by then). ).
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Administrators in Delhi, who continue to rely too heavily on antigen tests (last week, they accounted for 83% of the total 397,722 tests performed), could not have asked for a better demonstration of their inaccuracy (of the tests), and how errors the results could, in turn, have cascading implications. Delhi Prime Minister Arvind Kejriwal was in the House at the time, although it is unclear whether he came into contact with the infected lawmakers. A simple greeting or passing an infected person in the hall is unlikely to be dangerous – the infection comes from prolonged exposure. But, based on various research studies, a group of talking heads in a room are at more risk than a group of silent people.
I hope those Plexiglas partitions of Parliament are high enough.
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