Positive or negative: Self-test kits causing Covid confusion?

Rapid antigen self testing kits are flying off the shelves, say pharmacists in Delhi-NCR, but healthcare experts say that one must reconfirm the result with an RT-PCR, especially if one is symptomatic.
Covid-19 self testing kits have become quite popular among those wanting to check their Covid status at home. (Photo: Evelyn Hockstein/REUTERS; For representational purposes only)
Covid-19 self testing kits have become quite popular among those wanting to check their Covid status at home. (Photo: Evelyn Hockstein/REUTERS; For representational purposes only)
Published on Jan 23, 2022 02:09 AM IST
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BySiddhi Jain

New Delhi

As Covid-19 cases continue to be high in the Capital, various self-testing rapid antigen kits for Covid detection have been flying off the shelves. Many are picking up these self-testing kits from local pharmacists, to test whether the virus has affected them or not, in order to save themselves from anxiety and the time required in receiving reports from a test lab. But, is a negative or positive test result the ultimate correct answer? Well, healthcare experts warn against reading the results of self tests at face value.

The curious case of a false negative

Take the case of Anand Vihar-based Sanchit Sharma, who upon experiencing a mild headache and sore throat after a long day at work in a Noida-based MNC, stopped by a local pharmacy to buy an at home self test kit. To avoid “waiting time for RT PCR testing”, Sharma and his family tested at home using the instructions on the pack. The ‘negative’ was “the mood changer” according to him.

Sharma adds: “In the morning, my sore throat worsened and I developed a minor fever. Considering the situation, I immediately got my RT PCR done and the day after result shown was positive. It felt like I hit an iceberg. How can an ICMR approved testing kit be so wrong in showing the result? Now if anyone asks me, I’d suggest people not to rely completely on home based testing kits. Although the accuracy level of these kits have some error margin, but still the expectations of the people out there is much more at the moment and one must know that these aren’t final and binding.”

Pharmacists busy home delivering kits

Not only are the rapid antigen self-test kits flying off the shelves, but are also being ordered over home delivery as per many city-based pharmacies. Jai Bharat, who works in a Dwarka-based pharmacy, says, “Each day at least 20-30 people take home these tests. We’re also being asked to home deliver these kits. And we are regularly getting these kits supplied to us to cater to the high demand. There are different brands available and each costs between 250-300 per kit. But of course whenever anyone asks us whether their result is absolutely correct, we tell them we can’t take guarantee.”

A file photo shows the components of a Covid-19 rapid antigen self testing kit. (Photo: LOIC VENANCE/AFP; For representational purposes only)
A file photo shows the components of a Covid-19 rapid antigen self testing kit. (Photo: LOIC VENANCE/AFP; For representational purposes only)

Kits are useful like first aid

Delhi-based software engineer Suhaib Roomy, who had tested Covid positive recently, says he used the self-test kit to monitor the Covid status. “I was advised by my doctor to take a self test a couple of days after my symptoms subsided. I purchased a self test kit from a nearby chemist shop for 250. I had previously watched a video on YouTube on how to perform a self test. It was really easy and took me just two minutes to perform those steps. The result was shown in the strip within five minutes,” says Roomy. And Model Town-based accessory designer Akassh K Aggarwal says these testing kits did turn out to be a useful tool for him, adding: “It helped me diagnose my Covid positive status at home. I followed it up with an RT PCR lab test, and by the time the results came, my symptoms had gone from severe to mild.”

The doctor’s advice

Delhi-based Internal Medicine specialist Dr Shuchin Bajaj shares these kits are useful if used correctly. “We need to make sure to give out the right communication. First, you should know how to use them correctly. At home, some don’t know how to insert the probe correctly, or they’re taking the sample just from the outer part of the nose or tongue. Secondly, if the test shows a positive, then it’s a positive, but the rate of false negatives is quite high. It could be as high as 10-15%. If you are symptomatic, and it’s come out to be negative, please get it reconfirmed through an RT PCR test.” Adding that about 50% of his urban patients come to him having already self-tested at home, Dr Bajaj says it’s a cause of worry to not report the Covid positive status.

“Underreporting could be because of false negatives or faulty user behaviour. Even if they’re turning out to be positive, people are not reporting it to the concerned authority. These cases are escaping statistics. For instance, in some cases those using a test require the image of the kit to be uploaded after use, and then the app reports directly to the ICMR. But, most people are just visually inspecting the kit, and don’t upload the image. It could be because people do not want to isolate themselves for 14 days, when they are getting better in 4-5 days since it’s a mild variant. It’s also because there’s a social stigma around being Covid positive. People who have tested positive must be treated with compassion instead of making it look like they’re at fault if they have the infection,” the doctor says.

Take of the testing labs

Dr Shivali Ahlawat, Head of National Reference Laboratory at Oncquest Laboratories Ltd, which is “testing around 3,500-4,000 RTPCR samples daily” explains: “Home tests had good accuracy in case of a positive result, but could be misleading in case of a negative result. If a person has Covid like symptoms, she or he should get an RT-PCR test even if the home test came negative.”

Explaining the difference between the two, the expert says: “Rapid self-kit test detects protein fragments specific to the Coronavirus. While the rapid test can get you results very quickly, the results may not always be as accurate as the PCR. On the other hand, RT PCR testing is considered the most robust approach in SARS-CoV-2 detection. This test detects genetic material specific to the virus and can detect the virus within days of infection, even those with no symptoms. The test is generally done by a trained professional. Turnaround time is longer as compared to rapid test but results can come back in as little as 24 hours.”

Author tweets @siddhijainn

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