COVID-19: Reliability of India’s Self-Testing Kit Fuels Concern as False Negative Cases Rise

India’s apex body of biomedical research has approved the self-use Rapid Antigen Test (RAT) for COVID-19, but there are worries it may not detect new strains of the virus.

While the Indian Council of Medical Research (ICMR) has approved the self-use Rapid Antigen Test (RAT) for COVID (“CoviSelf”), its reliability is raising doubts, despite its cost-effectiveness and quicker results.

CoviSelf says users don’t need their samples to be collected by a medical professional but has advised against indiscriminate use of the kits, while the ICMR has reiterated that all symptomatic individuals who register a negative RAT test should get themselves immediately tested using RT-PCR (Reverse transcription – Polymerase chain reaction).

A woman with a breathing problem receives oxygen support for free at a Gurudwara (Sikh temple), amidst the spread of coronavirus disease (COVID-19), in Ghaziabad, India, April 30, 2021. REUTERS/Adnan Abidi

Meanwhile, false negative RT-PCR results for people who have COVID symptoms are on the rise – and the figure is much higher than that recorded during the first wave of the pandemic in India. 

Mylab Discovery Solutions, which developed CoviSelf, is stockpiling 10 million units of the recently-approved home test kits before a national rollout on 1 June, the media reports. 

In India, there are two types of approved tests for detecting COVID – RT-PCR and RAT, which is essentially a screen test.

Considered the gold standard COVID test, RT-PCR tests have a sensitivity of no higher than 70 percent, so many health experts are arguing that introducing a self-testing kit with a low sensitivity is pointless. 

Dr. Lancelot Pinto, a consultant pulmonologist at the P.D Hinduja Hospital & Medical Research Centre, told Sputnik: “Like other rapid antigen tests, CoviSelf has high specificity but its sensitivity is not very high. What this means is that in symptomatic individuals if the test is positive, no further confirmation is needed. However, if the person has symptoms and the test is negative, one needs to undergo an RTPCR test for confirmation. The advantage is the low cost and the ease of testing at home, thereby preventing exposure to other individuals at testing sites, some of whom may be infected and the other not infected individuals who stand a chance of getting infected by such individuals. It also reduces the exposure of technicians and lab workers to patients with the infection. However, indiscriminate use of the test should be avoided.”

He says the accuracy of any diagnostic test depends on the pretest probability of infection, which in turn, depends on the prevalence of the disease in those tested.

“When tested in asymptomatic individuals with no definite contact with an infected person, the accuracy of the test is likely to lower,” he adds.

There is also speculation fuelled by the theory that RT-PCR tests are failing to detect new strains of the virus. 

However, some experts have dismissed this idea, while the Indian government has also said that the presence of false negatives is not linked to the new SARS-CoV-2 variants.

This comes as several reports claim that over 20 percent of symptomatic Covid-19 patients are testing negative. This trend may be denying patients urgent medical care while enabling asymptomatic cases to spread the virus.

Due to this, doctors are recommending that anyone showing COVID symptoms be treated, irrespective of test results. 

Advantages of Self-Test Kits and Caution 

The self-test kits also have several benefits: they reduce testing backlogs in laboratories, lower costs, eliminate the need for sample collection from homes, and provide quicker results (within 15 minutes), leading to prompt treatment and isolation.

However, these tests are only effective if the patient follows the instructions correctly, interprets the results correctly, and isolates. 

In March this year, the European Centre for Disease Prevention and Control released a document saying that self-testing should complement but not replace traditional testing methods.

“Shifting the responsibility of reporting test results from health professionals and laboratories to individuals could lead to underreporting, and make response measures such as contact tracing and quarantine of contacts even more challenging,” it read. 

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