Another 65 cases of the Delta variant of the coronavirus have been detected in Karachi, taking the total to 100, after 35 cases were confirmed earlier.

The National Institute of Virology (NIV) at the University of Karachi, which tested 2,062 samples sent by the Sindh Health Department on July 12 and 13, said in a statement on Thursday that 163 results came back positive. Of these, genotyping of "randomly selected 94 positive samples of Covid-19 revealed 65 cases of Delta variant, which makes 69 per cent of total samples tested," it said.

Director of the International Centre for Chemical and Biological Sciences (ICCBS) at KU, Professor Dr Mohammad Iqbal Choudhary, while sharing the results, said that besides the Delta variant, two cases of the Beta (South African) variant, two cases of a wild-type variant and 25 cases of unidentified variants were also confirmed.

"The 25 [cases] may be Delta Plus variant or a new variant," the statement quoted Choudhary as saying. "The presence of Sars-CoV-2 Delta variant has already been confirmed in the Sindh province and its local transmission is evident from the recently identified cluster," he added.

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The statement noted that 15pc of samples collected between June 25 and July 9 had turned out to be Delta variant cases in a previous genotyping analysis. "Its proportion in positive cases is rapidly increasing," it observed.

"Researchers of the National Institute of Virology are constantly monitoring the spread of this variant in the metropolis, which is really a matter of concern," the statement added.

Earlier this week, the Sindh Health Department confirmed that 35 Delta variant cases were reported in Karachi.

It said "severe symptoms" of the virus had been observed in people who were confirmed to be suffering from the Delta variant.

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On Wednesday, the Sindh government reimposed coronavirus restrictions in the province, closing down schools and indoor dining, as Karachi's positivity rate was recorded as 17.11pc.

Over the last 24 hours, Pakistan recorded 2,545 cases — a massive 28.5 per cent increase over the 1,980 cases reported a day ago.

This is the first time the country has reported more than 2,500 infections since May 29, when 2,697 cases were reported. Of the new cases, 1,420, or 55.7pc were reported in Sindh.