India on Friday expanded its testing protocol to cover more people as contact-tracing of fresh coronavirus disease (Covid-19) cases revealed links to hundreds more, including senior politicians and bureaucrats still to show any symptom of the disease, even as experts said that an unexplained delay in extending the diagnostics to private labs meant the window to stop the virus from taking hold was fast slipping away.

Public health experts have repeatedly called for the pool of those being tested to be scaled up drastically and the private diagnostics mechanism to be opened up to people looking to get tested voluntarily.

With only 14,376 samples tested till Friday, the number was one of the lowest among countries that have tackled the outbreak. India can test 10,000 samples every day and experts say if this capacity remains underutilised, community transmission could go undetected. Community transmission is when the source of an individual’s infection can’t be traced and isolated.

A group of private labs that includes Dr Lal Path Labs, Dr Dang’s Lab, SRL Diagnostics, PathKind Labs, Metropolis Lab, and Syngene International submitted proposals to the Indian Council Of Medical Research (ICMR) to test people at for ₹5,000 on Thursday, but they are yet to get a response. “Private labs will get the approval for testing in the next three to four days,” said health minister Harsh Vardhan.

“We are well into exponential growth, which strongly implies community transmission… All these social distancing measures (close malls, work from home,…) can only buy time. There’s no point doing this unless you use the precious extra time to test, test, test and contain. Otherwise, when these measures are lifted, the outbreak will just flare up again,” tweeted Mukund Thattai, a computational biologist at the National Centre for Biological Sciences, Bangalore.

On a day the government expanded the scope of tests to cover asymptomatic people who have come in contact with positive cases, Uttar Pradesh health minister Jai Pratap Singh was tested for Covid-19. He recently came in contact with celebrity singer Kanika Kapoor, who recently travelled from London and attended several parties before being tested positive.

ICMR has so far tested only a handful of samples at random, all of them with severe acute respiratory infection (SARI). It was in the process of expanding guidelines to include testing all patients with SARI, which includes severe pneumonia, admitted in intensive care units (ICUs) across the country to track silent community transmission.

A Union health ministry directive said: “No suspected Covid-19 patient should be turned away from any hospital and the admission of any such patient should be notified to National Centre of Disease Control (NCDC) or Integrated Disease Surveillance Programme (IDSP) immediately.”

All India Institute of Medical Sciences director Dr Randeep Guleria, who chairs the ICMR expert committee on testing criteria of Covid-19, said: “With the numbers rising, we have changed the case definition of people being tested to include asymptomatic contacts of positive treating Covid-19 and SARI cases. Now all pneumonia patients must also be notified to NCDC or IDSP so that they can be tested for Covid-19 for community transmission surveillance.”

Community transmission, when a person with no travel history to a Covid-19-affected country or with known contact with a confirmed case gets infected, indicates that undiagnosed cases are infecting others, which is when infection clusters spiral out of control.

In anticipation of a surge in new cases, all government hospitals will run a mock drill on March 22 to measure clinical preparedness, infection control and inventory of equipment, including ventilators, which are critical to treat severe Covid-19 cases.