India reported one million cases of novel coronavirus and 25,000 deaths on July 16. In all likelihood, India will cross the two million mark today (August 6). Since crossing one million on July 16, most additional 1,00,000 cases have come in two days. Since July 30, the number of daily fresh cases reported has stayed above 50,000, with 56,626 cases being the highest reported for a single day (August 5).

India reported one million cases of novel coronavirus and 25,000 deaths on July 16. In all likelihood, India will cross the two million mark today (August 6). The cumulative number of cases reported as on August 5 was 19,63,239. The number of deaths had also increased to 40,739.

The U.S. has reported over 4.8 million cases, while Brazil has crossed 2.8 million. India has the third highest number of cases in the world. India reported the highest number of daily fresh cases in the world, surpassing the U.S and Brazil, on three consecutive days from August 2.

If it took three days to add an additional one lakh cases to cross 1.1 and 1.2 million cases, each additional 1,00,000 cases thereon have come in two days. Crossing from 1.5 million to 1.6 million happened in one day.  Since July 30, the number of daily fresh cases reported has stayed above 50,000, with 56,626 cases being the highest reported for a single day (August 5), surpassing the earlier record of 55,117 cases on August 1.

The number of people who have recovered from COVID-19 stands at 1.3 million, while the active cases is about 0.6 million.

Which States are driving the epidemic

Maharashtra (4,68,265) followed by Tamil Nadu (2,73,460) account for the highest number of cases in India. But Andhra Pradesh (1,86,461) and Karnataka (1,51,449), which had initially appeared to have contained the spread, have the third and fourth highest number of cases in the country. The other two States that have over 1,00,000 cases are Delhi (1,40,232) and Uttar Pradesh (1,04,388).

Over-reliance on rapid antigen tests

But what is of concern is the over-reliance on rapid antigen tests while the number of RT-PCR tests done has actually reduced the below the testing capacity. In effect, the rapid antigen tests have substituted RT-PCR tests instead of supplementing RT-PCR tests.

Rapid antigen tests have high specificity (99.3-100%) but low sensitivity (50-84% depending on the viral load of the patient) and so can throw up more false negatives, making the over-reliance on rapid antigen tests worrying.

It is due to the low sensitivity that on June 14, ICMR had recommended the use pf rapid antigen tests in “combination” with used RT-PCR. And it said: “Suspected individuals who test negative for COVID-19 by rapid antigen test should be definitely tested sequentially by RT-PCR to rule out infection, whereas a positive test should be considered as a true positive and does not need reconfirmation by RT-PCR test.”

As early as April 17, ICMR noted that RT-PCR is the gold-standard frontline tests for COVID-19 and rapid antibody test “cannot replace the frontline test. The rapid Antibody test is a supplementary tool to assess the prevalence of the diseases”.

The advisory sent out by ICMR as recently as June 23 once again stressed the importance of validating negative test results from rapid antigen tests using RT-PCR. It says: “Most of [rapid antigen] tests have relatively moderate sensitivity but high specificity. A positive test should be considered as a true positive whereas all symptomatic individuals testing negative through the rapid antigen test should be confirmed with a real-time PCR test.”

Elsewhere, the advisory again reiterates the same message: “All labs/hospitals initiating testing through the rapid antigen test need to ensure that all symptomatic negative patients should be essentially referred to a real-time RT-PCR test for COVID19. This is particularly essential as the rapid antigen PoC test has a moderate sensitivity.”

The trend of over-reliance on rapid antigen tests began in Delhi, where they account for about 65% of all tests performed daily. Only 1 in 200 of those who tested negative in an antigen test in Delhi were retested with RT-PCR, a report in The Hindu says. Delhi carried out 305,820 rapid antigen tests between June 18 and July 16. Of these, 285,225 tests were negative. Of those tested negative, only 1,670 (or about 0.5%) were retested by RT-PCR. Of those retested, 262 tested positive by RT-PCR.

Now, Andhra Pradesh and Karnataka too have begun to do more rapid antigen tests at the expense of RT-PCR. According to ICMR, rapid antigen tests now comprise 25-30% of the tests carried out in India, Dr Balram Bhargava, Director-General of ICMR said at a press briefing on August 4.

Thanks to the low sensitivity, the over-reliance on rapid antigen tests is a sure to reduce the test positivity rate, making it appear that the number of infected people in the community is less. Using a less-reliable test is surely not the way to fight the virus spread.

Rapid Antigen Tests (RADT) have been increasingly used by States to quickly find #COVID19 infections. But rather th… twitter.com/i/web/status/1…—
Srinivasan Ramani (@vrsrini) August 06, 2020

That sero-survey carried out in Delhi revealed that nearly 23% had been infected, the actual number of people who have been tested positive (1,40,232) is a mere 0.59% of the population.