661 new cases in Gurugram district, total count reaches 46,555
The Covid-19 count in Gurugram district reached 46,555 with 661 new cases reported on Wednesday, according to health department data. Active cases rose to 6,181 while the death toll stood at 272 as three deaths related to the SARS-CoV-2 virus were confirmed on Wednesday.
To flatten the curve of new infections, the health department said it has ramped up overall testing, while gradually increasing the proportion of rapid antigen tests. However, according to experts, a higher percentage of rapid antigen tests masks the accurate prevalence of the disease due to its poor accuracy in detecting cases.
Data shows that in the last one week, rapid antigen tests have increased by almost 16 percentage points. Out of the total 47, 795 tests conducted in the last one week, nearly 27% were antigen tests. If compared to the previous week, the proportion of antigen tests was just 11% when more than 25,000 tests were being administered.
The daily average, including 4,500 tests conducted in a single day on November 21, shows nearly 1,800 rapid antigen tests have been conducted every day in the last one week, out of the 6,000 overall tests administered in a day. On Wednesday too, at least 6,284 Covid-19 tests were administered, of which 4,873 were the gold standard Revers Transcription Polymerase Chain Reaction (RT-PCR) and 1,411 were rapid antigen.
The rapid antigen test has to be done in high-risk areas with repeat testing to control the transmission of the virus. Due to its poor accuracy in identifying true positives, the test is generally not preferred. Studies shows that increased antigen testing impacts the test positivity rate - total number of positive samples of the total samples collected – an important indicator to gauge the prevalence of infection.
In the last one week, due to the increased rapid antigen tests, the weekly positivity rate has even come down to almost 12%, compared to the previous week positivity rate of almost 17%. Scientifically, it has been one of the major drawbacks of antigen tests that it masks the exact positivity rate.
Experts suggest that positivity rate through RT-PCR and rapid antigen tests should be separately calculated to have a clearer picture of the prevalence of infection. “Gurugram should declare break up of tests done, cases detected through RT-PCR and rapid antigen tests, respectively, on a daily and a cumulative basis and show their positivity rates separately to present more accurate picture,” said Dheeraj Singh, a data scientist who has been monitoring district’s Covid-19 data.
An antigen test can detect coronavirus disease cases only when the viral load is high. In some cases, it even misses out the symptomatic person. Therefore, as per the Indian Council of Medical Research guidelines, it is mandatory to conduct RT-PCR for every rapid antigen negative test. However, it is left to the decision of the lab technicians at the time of testing based on the symptom of the suspected cases.
A record 37,244 tests were administered across the state on Wednesday, with Faridabad conducting the highest sample collection of 14,209 on Wednesday.
The state health department has decided to observe November 28 as sampling day across the state. Rajeev Arora, additional chief secretary, state health department, said, “The target is to do a minimum test of 50,000 tests across the state, of which 80% should be RT-PCR. Health health department has been directed to tie up with labs in advance. The sampling would be targeted as well as random.”
He said that the Haryana Medical Service Corporation Limited will ensure the supply of Viral Transport Medium kits and other materials.
More than 30,000 tests are administered across the state every day. According to the state health bulletin, 3,269,677 tests have been administered in the state till Wednesday, of which 88% tests have been conducted by government labs. Sirsa, Panipat, Ambala, Narnaul and Panchkula have conducted the fewest tests in the state. Earlier this week, senior state officials clarified that testing will be specifically increased in Gurugram, Faridabad, Hisar and Rohtak, where cases are highest in the state.
Dr Virender Yadav, chief medical officer, Gurugram, said, “Based on the resources available, the department will chalk out the strategy for the upcoming sampling day on November 28. We will have to consider logistics, availability of manpower and delivery of test results within 48 hours if a record number of RT-PCR tests are to be administered. Sites where testing camps will be held will be decided on Thursday.”