Daily Covid-19 tests inch closer to targeted 1 million mark
Experts say that to control the outbreak, aggressive testing is crucial. In this case, the number of Covid-19 cases diagnosed in the country is likely to see an increase before it starts seeing a dip, indicating that the spread is slowing.Updated: Aug 14, 2020, 05:53 IST
India tested in excess of 800,000 samples for the coronavirus disease (Covid-19) on Wednesday, inching closer to its target of conducting a million tests a day even as infections of the viral disease have continued to mount steadily.
In total, India has performed 26.8 million tests since January 22 when Covid-19 testing started with one lab at the Indian Council of Medical Research’s National Institute of Virology in Pune. As of Thursday, testing is being done in 1,433 labs across the country — 947 in the public sector and 486 private ones.
Experts say that to control the outbreak, aggressive testing is crucial. In this case, the number of Covid-19 cases diagnosed in the country is likely to see an increase before it starts seeing a dip, indicating that the spread is slowing. Until Thursday, India recorded 2,459,275 cases and 48,140 deaths.
India has conducted 20,140 tests per million residents — much lower than other countries that have comparable caseloads. In comparison, the United States and Brazil, the only two nations with more cases than India, have conducted 204,130 and 62,197 tests for every million residents.
The country’s target of conducting a million tests a day would mean that it would be conducting 750 tests per million per day — significantly higher than the World Health Organization (WHO)’s recommendation of 140 tests per million residents a day. To be sure, India is still testing much above the WHO advisory – in the last week, the country has tested an average of 503 people per million every day.
For the week ending August 12, India’s daily tests have increased by 2.8% every day on average. This number was the same the week before that. If this rate of increase in daily testing remains constant, then the country may touch the 1 million-daily-test mark in 12 days, according to HT’s projections.
The four highest single-day tests conducted across the country have all been reported in the past five days — 830,391 daily tests on August 12; 733,449 on August 11; 719,364 on August 8 and 698,290 on August 9 – highlighting the recent increase. On August 9 (Sunday) 477,023 samples were tested. To be sure, Sundays are historically days when daily testing drops as many labs function with low staff and few people step out. “India’s ‘test, track and treat’ strategy has helped us bring down the fatality rate from its peak of 3.36% on June 17 to 1.96% within two months... We have been ahead of all our testing targets. The target of 100,000 tests was May 31; we crossed it on May 10. In July-end, I said in an interview that the target was to reach a million tests in 12 weeks, we are geared to reach it in two to three weeks,” Union health minister Harash Vardhan said on Thursday. A July 7 column in this newspaper suggested a target of a million tests a day.
“We are trying our best to meet the target (by August-end),” said ICMR director general Dr Balram Bhargava.
The recent increase in testing has also brought down the weekly average positivity rate — the fraction of tests that come back positive — in the country from 12.5% (the highest recorded so far) on July 25 to 9.4% on Thursday. Overall, 8.9% of all tests in the country have come back positive.
According to WHO recommendations, the positivity rate from a region that has a comprehensive testing programme should be at or below 5% for at least 14 days before it can be assumed that an outbreak is under control and lockdowns can be relaxed.
Much of the recent increase in testing can be attributed to the growing role of antigen tests in the states. Antigen, or rapid, tests usually provide results within hours and are relatively cheap. These kits are designed to detect antigens (substances in our bodies that stimulate an immune response) and can be performed in mobile stations and don’t necessarily need labs. The downside is that they have a far higher chance of returning false negatives (showing infected people as uninfected), and thus can let cases slide under the radar.
The real-time reverse transcription polymerase chain reaction (RT-PCR) test, on the other hand, is the gold-standard for Covid-19 testing and is the most definitive test available. It is used for the detection of nucleic acid from Sars-CoV-2 and is based on PCR, a process that duplicates and amplifies genetic fragments of the virus, so that it becomes easily detectable. The downside is that the process, from samples collection to results, for these can generally take 24-48 hours and needs dedicated machines.
During the weekly Covid-19 press briefing on August 5, Union health ministry officials had said that antigen tests accounted for at least a quarter of all tests conducted in the country until then.
ICMR has also said the proportion of antigen tests is increasing. “When we started, antigen tests comprised only 5-6% of the total tests, but this proportion is consistently rising. Today, total antigen tests are nearly between 25-30% tests of the total number of Covid-19 tests done so far,” Dr Bhargava said on August 5.
Only four states — Andhra Pradesh, Delhi, Karnataka and West Bengal — give a breakup of testing numbers based on antigen and RT-PCR/other nucleic tests. Among them, of the 1,034,537 samples tested in the last week, a majority (50.3%) have been antigen tests.
HT has repeatedly pointed out that antigen tests are best used when time is a constraint and results are needed quickly -- in a containment zone or a hot spot, for instance.
In terms of states, the wide disparity in testing rates remains as higher-than-average testing states have continued to fuel the nationwide boost to testing numbers in the past weeks. Among the 20 major states, Assam has conducted the highest number of tests in the country for the week ending on August 12 — 10,649 tests per million. Andhra Pradesh features on the second spot with 7,930 tests per million in the last week, followed by Delhi, with 7,210 tests per million. To be sure, these states all have a testing rate that is higher than the national average.
At the lowest end of tests in the last week, are Jharkhand, Madhya Pradesh and Chhattisgarh with 1,360, 1,384 and 1,702 tests per million. And much like the top, these states have overall lower-than-national-average testing rates. Bihar, the state with the lowest overall testing rate, appears to have improved its testing in the last week – the state tested 4,467 samples per million in the last week against the national average of 3,523.
“For a small state like Assam we have been crossing several milestones in testing. On July 30, we conducted 50,000 tests on a day and on August 4 we did more than 75,000 tests. On August 12, we had kept our target as 100,000 tests, but when we tallied the figures at the end of the day, we found we conducted more than 1.43 lakh tests. We were quite surprised,” said Assam’s principal secretary (health) Samir Kumar Sinha. “This has required lot of mobilisation, lot of people on the ground, large number of test kits. Nearly 90% of the tests that we are doing these days are rapid antigen tests and the rest RT-PCR,” Sinha said.
Andhra Pradesh commissioner of health Katamaneni Bhaskar said only around 40% of the tests being done are rapid antigen tests. Out of 55,692 tests done on Thursday, only 26,000 tests were antigen tests. “We have been doing antigen tests only as per ICMR guidelines. And they are also reliable. If a person tests positive in antigen tests, he is positive for Covid-19,” Bhaskar said.
Officials in Bihar said they have been working on increasing their testing rate. “We are increasing our testing every day. During the last 24 hours, 104,452 people were tested and so far 137,742 tests have been conducted in the state,” the state’s principal secretary, health, Pratyaya Amrit said.
Experts, however, said that other than ramping up the number of tests, the pricing needs to be controlled as well. “There is a need to increase testing for Covid-19 across the country as our testing per million still continues to be low. For this, we need not only trained staff but the cost of the testing has to be brought down further. An RT-PCR test costs about ₹2,400, it needs to be brought down to about ₹1,000. It can be done through bulk procurement by one agency for the entire country and scaling up manufacturing,” said Dr SK Sarin, director, Institute of Liver and Biliary Sciences, New Delhi.