"When antigen test is supposed to use only in containment zones and to be repeated with RTPCR test, Delhi governments strategy of heavily resorting to antigen tests without conducting subsequent RTPCR tests may undermine the containment strategy. The serological survey result estimated around 50 lakhs are infected when only 1.3 lakhs are confirmed positive using the RTPCR tests, is making lives of 77% of Delhites vulnerable to covid. It calls for revisiting the method of testing to contain the pandemic effective."
The fatality rate is the lowest in the world and the news of sudden flattening of the curve is offering lots of space for complacency to Delhiites. Undoubtedly the Delhi-Delhi duo is behind this magic and Delhi is best in the country with respect to the covid containment strategy. Imagine, we are admitted in a hospital and an avaricious or naive doctor says that an immediate surgery is required to save our life. Very likely, we will give a green signal to save our life as we are unaware about our condition and presuming that we are in threat. Later, we realized that nothing was serious. This is an unresolved dilemma in the health sector.
Testing Strategy
Data is the oil of the era and a single data point can make a huge impact among millions, as many decisions are hovering around this which is applicable to covid strategy of test, treat and track as well.
There are two types of covid test, RT-PCR/Reverse transcription polymerase chain reaction (Viral) and Rapid Antigen Detection Tests (RADT) or antigen test. Antigen tests are very fast but RT-PCR test is longer and complex. The antigen test hints the possibility of infection by finding the presence of viral proteins , but its absence does not mean the person is not infected, hence ICMR and other agencies cautioned to limit this antigen test only in containment zones or high spread regions and to do RT-PCR followed by antigen test, whereas the RT-PCR test looks for the RNA of the virus and its results are mostly accurate and reliable. Despite these facts, Delhi Government hugely resort to antigen tests (75%) and conduct tests at random places which may derail the containment strategy.
Delhi was at the peak during the end of June which sharply dwindled after. As per the report by the Hindu, Delhi formally began using antigen testing kits on June 18 and has accelerated their use since July. From June 18- July 16, Delhi has conducted 305,820 antigen tests, Of these, 285,225 tests came ‘negative’. Of them, 1,670 (1/200 or about 0.5%) were chosen for re-test by RT-PCR and 262 of these were confirmed positive. However, of those re-tested with RT-PCR, around 15% test positive, which is higher than the antigen test positivity of 6%;report says. It's alarming as the testing strategy is more relied on less unreliable antigen tests ( Affidavit by Delhi Government says 2-3 antigen test for one RT-PCR ) when antigen tests are limited to high risk zones only as it may miss as many as half of those who are actually positive. That is, if antigen tests account for most of Delhi's increased testing rates, they may be missing a lot of cases, driving the case numbers down.
In fact, India's current testing guidelines require that anyone who tests negative for the virus must be retested with an RT-PCR kit. So the question is how many tests of each kind is Delhi doing, and is everyone being retested? Asks K Srinath Reddy, president of the Public Health Foundation of India and member of the national Covid-19 taskforce. This is very misleading in the context of nearly 90% covid cases are asymptomatic.
50 Lakhs infected ?
The serological survey conducted in Delhi assumed that around 23 per cent (around 50 lakhs) which means as many as one in every four Delhi citizens have already been exposed to the virus. This result is surpassing the possibility of infection (15%) as per the random antigen tests. When the total number of confirmed positive cases in Delhi so far is around 1.3 lakhs and the probability of infected as per the serological survey is around fifty lakhs, this is a healthy emergency as 77% are vulnerable to the virus. It also revealed that a PCR test caught only about 1 in 50 who are infected by the virus. This undermines claims by the Delhi government of its ability to contain infection spread. The Hindu reported.
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