Around 9.45 lakh people are being monitored under the Integrated Disease Surveillance Programme (IDSP) and upon detection of COVID-19 symptoms, samples are taken from them for testing, the Union health ministry said on Friday.
At the government's press briefing on the COVID-19 situation, Director of the National Centre for Disease Control (NCDC) S K Singh gave a presentation on how surveillance is being used to gather epidemiological intelligence and take required measures accordingly, and said surveillance has been the country's "primary weapon" in the fight against novel coronavirus.
"Around 9.45 lakh possibly infected people across the country are under surveillance based on data collected from 734 districts. They are being closely monitored and samples are taken from them promptly upon detection of symptoms," he said.
"Earlier, we used to screen those coming from abroad at the airports, sea ports and land check posts. Even if they showed no symptoms at that time, we would monitor them once they return home and keep a check on their health on the basis of the data shared by the Bureau of Immigration.
"We would share the data with the states and districts, and they would keep those people under surveillance. We also initiate contact tracing immediately after a person is found infected," he explained, and gave an example of how people who had come in contact with those who attended the Tablighi Jamaat event in Delhi were traced in 20 states and Union Territories.
Starting from ban on international flights to stop transmission of coronavirus infection from abroad, graded steps, including lockdown and ramping up of testing, helped in containing the spread of the virus, Singh said.
Surveillance network has been set up at district level as well, so that household survey, quarantine and isolation are done as part of cluster containment plan, the NCDC director said.
He said a live dashboard has been set up for real-time surveillance and how it directly captures data on logistics, hospitals and isolation beds from districts.
"Through this system, we also analyse the requirement of logistics, PPE kits, manpower and resources according to the need depending on the number of cases."
The country initiated surveillance mechanism even before the first COVID-19 case was reported in India. It played an important role in containing the spread of the infection, Singh said as he highlighted the importance of social distancing and how lockdown played an effective role in breaking the chain of transmission.
The death toll due to the novel coronavirus rose to 723 with 37 fatalities reported since Thursday evening, while the number of cases saw a record jump of 1,752 to go up to 23,452 cases on Friday, according to the Union health ministry.
The previous highest single day increase was on April 20 when 1,540 cases were reported.
However, a PTI tally of the figures reported by various states as on Friday showed 24,356 cases and 778 deaths in the country.
There has been a lag in the Union Health Ministry figures, compared to the number of deaths announced by different states, which officials attribute to procedural delays in assigning the cases to individual states.