“We should keep in mind the timing of the RT-PCR test and the type of the test. The sensitivity of the Rapid Antigen test is far lower than the traditional RT-PCR. So, if there are symptoms, a negative Rapid Antigen test should be followed with an RT-PCR,” said Dr Arjun Dang, the CEO of Dr Dangs Lab.

This comes in the backdrop of doctors warning that there are chances of false-negative reports in Rapid Antigen home testing kits even after having Covid symptoms and people should self-isolate themselves as a precaution.

“There are two kinds of tests that are being done. One is the home tests, which are the rapid antigen tests and these have quite a limited sensitivity. These are about 505 as sensitive as the gold standard RT-PCR test, so you may get a false negative test on these testing kits,” Dr Harsh Mahajan, the founder and chief radiologist of Mahajan Imaging, was quoted as saying by news agency ANI.

He said in many cases, false-negative has been reported even after showing symptoms of Covid.

“In these home test kits, there are chances of not taking proper sampling from the back of nose or throat. As result, a ‘positive’ result might not come. The chances of false-negative reports in RT-PCR tests are only 10% since tested are done in the lab,” he said.

Mahajan further said when a patient is symptomatic, then, by and large, the RT-PCR test comes positive if the sample is obtained properly and transportation is done properly.

“Sometimes test results come negative because of the duration of the incubation period. The incubation period is different for both the variants Delta and Omicron. During the Delta variant, the rough average incubation period was about five days. So, we used to tell people not to get tested immediately after exposure because they would come negative. It does take between two to 14 days of incubation with an average of five days,” he explained.

The central government had last month said that two lakh of the Rapid Antigen test were used in the first 20 days of January while just 3,000 were utilised last year.

“Testing commodities are in plenty, whether it be for RT-PCR, whether it be for rapid antigen tests or for home antigen tests, or ancillary equipment like viral transport medium or RNA extraction kits. What is important is that we have noted an increase in uptake of home tests,” said ICMR director-general Dr Balram Bhargava.

“In the whole of last year, only 3,000 home tests were recorded and in these 20 days, we have seen two lakh home tests which have been used,” Bhargava added.