NEW DELHI: The number of fresh COVID-19 cases in Delhi went from 356, the city's highest, on April 13 to 17 just two days later on April 15, a fluctuation that experts say points to the pace of contact tracing and a possible indication the infection has not gone to the community.
The erratic numbers also reflect the time taken four to five days -- for results of the RT-PCR test being used in India currently since the rapid anti-bodies test kits are yet to arrive, the experts said.
On Wednesday, the total number of coronavirus cases in the national capital went up by 17 to 1,578 cases, according to Delhi government authorities.
Two death were also reported, taking the toll in Delhi to 32.
There is no discernible trajectory in the last few days with the number of cases going up and down erratically.
On April 10, the city recorded 183 fresh cases, including 154 from the Tablighi Jamaat congregation in Nizamuddin.
On April 11, it was 166, April 12 (85), April 13 (356), April 14 (51) and April 15 (17).
"The good thing about the fluctuation in cases is that it means the infection has not gone to the community level in Delhi.
Otherwise, the fresh cases would have only steadily increased," said Vikas Maurya, director and head, Department of Pulmonology and Sleep Disorders, Fortis Hospital, Shalimar Bagh.
Last month, government authorities carried out measures to quarantine people who were related to the congregation that took place in Nizamuddin area in March.
"If you look at the initial spike, it is clear that most cases are from the Nizamuddin area after that religious congregation.
And contact tracing of people who may have contracted the disease takes time.
So those cases reflect later once the test results are out.
This takes four-five days," Maurya said.
Tracing of people who came in contact with infected people takes time.
Therefore, the data of people who may have been infected a week ago will be added only later once the results come out, added another doctor at a leading private hospital on the condition of anonymity.
Two kinds of diagnostic tests have been prescribed for use in India, RT-PCR (reverse transcription-polymerase chain reaction) and rapid antibodies test.
While RT-PCR test is being used currently, rapid anti-bodies test kits are still awaited from abroad, he said.
"If the rapid anti-bodies tests begin, our screening process will get expedited and more cases can be traced and detected in shorter period of time," he added.
A RT-PCR test is a laboratory technique combining reverse transcription of RNA into DNA that detects the virus.
The antibody tests, which use blood, detect the body's response to the virus.
"The rapid anti-bodies test takes less time and results can come in 20-30 minutes.
But till the kits do not come to India, RT-PCR tests are being used in hotspots and other high-risk areas, so results reflecting later, hence the variation in data," he said.
Delhi so far has 56 containment zones that have been sealed by authorities.
Sample collection for the high-risk areas in identified containment zones for people who had come in contacts with persons testing positive is being carried out, Delhi Health Department authorities said.
According to the department, of the total 1,578 cases recorded till April 15, at least 867 are admitted at various hospitals, including LNJP Hospital, GTB Hospital, Safdarjung and the Rajiv Gandhi Super Speciality Hospital.
The total number of COVID-19 samples sent till date stands at 16,605.
On April 15, the corresponding figure was 11,061.
Experts on Wednesday said India needs to "significantly ramp up" the number of testing done across the country to trace COVID-19 cases if the pandemic is to be contained in time.
The death toll due to coronavirus rose to 414 and the number of cases to 12,380 in the country on Thursday, according to the Union Health Ministry.
As many as 2,517 people have been kept in quarantine at various government facilities here, the Delhi health department said on Wednesday.
A total of 30,451 people who came in contact with affected persons, are under home quarantine till date and 18,464 have completed their 14-day quarantine, they said.