With 54,449 confirmed cases of the novel coronavirus in the State, as on June 19, Tamil Nadu has the second highest numbers recorded after Maharashtra (over 1,20,500). Delhi closely follows with nearly 50,000 cases. The number of new cases recorded in Tamil Nadu, especially in Chennai, has been steadily rising.

Deaths too have increased, from 87 on May 20 to 666 on June 19, a 16-fold increase. While there were just three deaths on May 20, the figures increased steadily but remained under 20 till June 12, except on June 11 when there were 23 deaths. If the toll crossed 30 on June 13, for the first time, it has been above 40 since June 15.

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From 13,191 total cases and 743 fresh cases reported on May 20, the State crossed the 50,000 mark on June 17 with a record 2,174 fresh cases on that day — the first time the number of cases reported on a given day have crossed 2,000; June 18had 2,141 cases. It was on May 31 that Tamil Nadu crossed the 1,000 mark, with 1,149 cases.

More testing

But the State has been increasing the number of tests carried out each day since May 20. From 11,894 tests on May 20, Tamil Nadu has ramped up testing with each passing day to reach nearly 25,500 on June 17, a sharp increase from 19,200-odd cases the previous day. June 18 witnessed a further increase to 26,736. So far, Tamil Nadu has carried out 8,00,443 tests as on June 18, which is higher than Maharashtra, with 7,19,637 tests.

The test positivity rate which has been steadily increasing since June 1, reaching a peak on June 9 with 12.7%, has been reducing since June 14 when the number of tests each day has been climbing; it was 8.5% on June 17. At 10,371 tests per million population, Tamil Nadu is among the top six States.

A high test positivity rate reflects either good surveillance or higher spread of the virus in the community. According to Prof. Giridhara R. Babu, Head – Lifecourse Epidemiology, Indian Institute of Public Health, Public Health Foundation of India, Bengaluru, it could be a combination of good surveillance and higher prevalence of the virus in the case of Tamil Nadu. But he is quick to add that surveillance could have remained constant and not drastically changed in a matter of a few days and hence the increase in test positivity is more a reflection of the higher prevalence of infected people in the community. Test positivity can also reduce when the number of tests carried out is increased and the testing is not based on syndromic surveillance.

The only way to reduce the true prevalence of infected people in the community is by further ramping up testing, contact tracing and quarantining of contacts and isolating those who test positive.

Having squandered the opportunity to contain the spread during the extended lockdown, the State now has a second chance to make up for it during the complete lockdown for 12 days that began on June 19.

Go door-to-door

The most important departure that Tamil Nadu needs to make is to actively look for cases in Chennai and certain parts of three adjoining districts (Chengalpattu, Kancheepuram and Tiruvallur) where the most cases are being reported. There is compulsion to carry out door-to-door surveillance and test anyone who shows even one of the 15 COVID-19 symptoms recognised by the Health Ministry, including a loss of smell and taste, which was recently included. Currently, a person needs to exhibit a combination of symptoms to become eligible for a test.

Another important shift in strategy should be in testing widely without insisting on a person’s travel history or contact with a known positive case as a prerequisite for testing. The need of the hour is to move away from the restrictive categories of people eligible for a test to a more liberal and inclusive protocol that allows more people to be tested.

Aggressive testing and isolation of infected people alone will be insufficient to contain the spread unless it is carried out in a short span of time. With each infected individual capable of spreading the virus to more people, concerted efforts are needed to quickly trace, test and isolate the infected.

Lessons from Dharavi

While the majority of cases in the State are restricted to Chennai and three adjoining districts — thus making the task of containing the spread relatively easy — the areas in Chennai where more cases are being reported are those that are chock-a-block with people. That crowded neighbourhoods enable easy spread of the virus is the reason why aggressive screening, testing and isolation need to be carried out in double quick time. If the virus spread in Dharavi, Asia’s largest slum, in Mumbai, can be controlled, there is no reason why Tamil Nadu cannot achieve the same feat.

Proactive screening door-to-door, aggressive testing, quarantining of people suspected to be infected and isolation of those testing positive helped contain the virus spread in Dharavi. In addition, the Brihanmumbai Municipal Corporation established fever clinics for the early detection of cases.

prasad.ravindranath@thehindu.co.in