The BMC chief said most of the patients are asymptomatic.
As India's financial capital braces for 10,000 fresh Covid cases a day, random tests are being conducted to arrest the spread of the infection. On Tuesday, random tests were conducted at the sessions court in Mumbai.
With the fear of Covid spreading, the Brihanmumbai Corporation has decided to ramp up testing. The Centre wants states to do 70 per cent of the more reliable RT-PCR tests.
"RTPCR is preferred. And of number of tests, 70 per cent tests should be RTPCR," the Union health secretary said in Delhi this evening.
NDTV analysed the data for a week till March 28, which showed that about half the Covid tests are the less-reliable antigen tests, rather than the gold-standard RT-PCR.
The RT-PCR has a much higher positivity rate, so much so that if all tests conducted last week were RT-PCR, there would be roughly 50 per cent more cases. This means that instead of an average of a slightly below 4,000 cases daily, there would be almost 6,000 cases.
Mumbai's municipal chief said they do not have the capacity to conduct more RT-PCR tests.
"We have exhausted our RT-PCR capacity, and we would love to enhance this further but now we can either stop at that or increase our chances with RAT, so that we can at least have the chance of finding more positives," BMC Commissioner Iqbal Chahal told NDTV.
"Our positivity is 14 per cent currently. We are going to increase our testing to 60,000 by Thursday. So the figure can go up to 10,000, he said.
There is nothing to worry as "most of the patients are asymptomatic," he added. In the current situation, that might be the silver lining, as authorities are scrambling for more hospital beds.
But the danger of false negatives is that people can roam around freely spreading the virus and to arrest the spread, as the union health ministry is advising, it is important for the BMC to increase the capacity for RT-PCR tests.
The second wave of coronavirus in Maharashtra started on February 10 and till March 20, Mumbai logged 85,000 cases, said Mr Chahal has said.