Barricades are seen at the Turkman Gate on day nineteen of the 21 day nationwide lockdown to check the spread of coronavirus, in New Delhi, on Sunday, April 12, 2020. (Sushil Kumar/HT PHOTO)
The Delhi government has decided to scale up rapid tests for the coronavirus disease (Covid-19), senior government officials familiar with the matter said, and is waiting for the antibody test kits that were due to arrive on Friday to start more aggressive and random testing in all containment zones across the city.
Delhi has 43 containment zones, which includes lanes and localities across the city. Two of these — Nizamuddin Basti and Dilshad Garden — are designated virus hot spots. Officials said that the government has roped in eight medical institutes to oversee the testing process in different parts of the Capital, which is divided into 11 revenue districts.
The random tests will be done using rapid antibody kits – these are capable of showing results within 20-30 minutes – and the sample size will depend on the size of each containment zones, said a senior officer in the health department who asked not to be named.
While some containment zones in Delhi consist of a single building, plot or lane, few others include mazes of lanes and even arterial roads. The area of each containment zone was demarcated on the basis of cases recorded, a threat assessment, and an expected rate of transmission given the geography of the locality.
By random sampling, the government intends to take the testing exercise beyond individuals who have a travel history to Covid-19 affected countries, or the direct contacts of individuals who have tested positive so far.
According to Jugal Kishore, head of the community medicines department in Safdarjung Hospital, who is leading one team concerning the monitoring of the rapid test exercise about to start in containment zones, said that the primary objective of the scheme is “an accurate assessment of the burden of the disease” and “containment of community transmission”.
“In each containment zone, patients with severe acute respiratory illnesses (SARI) will be prioritised for the test. The rest of the sample size would be random in nature,” Kishore added.
In an interview to HT last week, health minister Satyendar Jain had said that 100,000 rapid testing kits were ordered, and that these would be used to conduct tests starting with the two hots pots and then among health care workers, which include doctors, nurses, orderlies and sanitation employees.
The government has now decided to expand this to all containment zones. With 85 new cases on Sunday, Delhi recorded 1,154 Covid-19 cases, including 24 deaths.
In the same interview, Jain had said that the government was also looking at “pool testing”, in which the samples of several people could be mixed before testing so that the process of eliminating those who don’t have Covid-19 could be speeded up.
On April 7, chief minister Arvind Kejriwal said that the Union government had allotted 27,000 rapid testing kits for Delhi and the batch would arrive by April 10.
“It has not happened yet. We checked with the ICMR (Indian Council for Medical Research) because the kits have to come through them. They said that even they have not received the allotted batch. We are expecting the kits this week,” said second officer in the health department who spoke on condition of anonymity.
Unlike the RT-PCR test currently in use that detects the virus’s genetic material (RNA) in throat swabs to diagnose a current Covid-19 infection, rapid antibody tests indicate if a person has been infected in the past and has developed and immunity to the virus. Experts say they can also be used as a screening test for the infection — antibodies typically show up a week after the infection.
The simple blood test (samples can be collected by just a finger prick) which takes 15-20 minutes to give results, identifies people who were infected at least a week before the test, and also those who were infected but never diagnosed, helping map undetected infections and giving the correct extent of the spread of the disease.
Charoo Hans, former head of the microbiology department at the Ram Manohar Lohia Hospital, said: “It is essential to prioritise testing of households with SARI cases and other possible contacts, such as people providing essential services in those containment areas. However, as asymptomatic individuals can also test positive for Covid-19 it is also essential to test these individuals on random basis. Data generated by such studies will help in understanding the burden of disease and the possibility of community transmission.”
Community transmission is the third of the four stages of the spread of an infectious disease. The first is travel history, the second is local transmission, the third is community transmission, and the fourth is epidemic. India has so far maintained that the disease is in the second stage, or between stage two and stage three with “limited community transmission” in some clusters.