Delhi chief minister Arvind Kejriwal said on Saturday the Capital is following strategy of “very aggressive testing and isolation” and conducted the highest number of Covid-19 tests in a single day on Friday.

The national capital, which has overtaken Mumbai in terms of the number of Covid-19 cases, has seen a surge in infections prompting the Centre to ramp up efforts to contain the spread through a five-pronged approach.

“Delhi conducted highest no of tests in a singly day yesterday- 21,144. We have increased testing 4 times. Delhi now following strategy of very aggressive testing and isolation,” Arvind Kejriwal tweeted.

The Aam Aadmi Party (AAP) leader’s post came on a day authorities will begin a massive mammoth serological survey or sero-surveillance study to determine the spread of the coronavirus disease.

The serological survey will be conducted in all the 11 districts in Delhi between June 27 and July 10 to enable authorities to undertake a comprehensive analysis of Covid-19 and then prepare a broad strategy to combat the pandemic.

Authorities have already begun a house-to-house screening of people in at least five revenue districts of the Capital on Friday, according to the Covid-19 management plan chalked out after a meeting chaired by Union home minister Amit Shah last Sunday.

The aim of the screening exercise is to identify people with Covid-19-like symptoms, create a comprehensive database and then get them tested.

It involves checking people for signs of flu such as fever, sore throat, cough and asking them about their travel history to map the virus.

Delhi has recorded 77,240 Covid-19 cases and 2,492 deaths so far, according to the Union health ministry’s coronavirus dashboard.