Science

‘Shutdown alone is not enough to break the chain’

Giridhara Babu

Giridhara Babu   | Photo Credit: Special arrangement

In an unprecedented measure, India on March 25 began a country-wide shutdown for 21 days to cut the transmission chain of the novel coronavirus (SARS-CoV-2). Till Wednesday, India had adopted the containment measures of screening, testing, isolating and tracing contacts.

On March 25, The WHO Director-General Tedros Adhanom Ghebreyesus said: “Shutting down population movement is buying time and reducing the pressure on health systems. But on their own, these measures will not extinguish the epidemic. The point of these actions is to enable the more precise and targeted measures that are needed to stop transmission and save lives.” Among other measures every country should take, the WHO chief said the production, capacity and availability of testing has to be ramped up, and a system to “find every suspected case at community level” has to be implemented.

Giridhara Babu, Head of the Lifecourse Epidemiology at the Public Health Foundation of India, Bengaluru, in an email to The Hindu explains how the shutdown along with testing can help flatten the curve.

Prime Minister Narendra Modi said 21 days of lockdown will help cut the transmission chain. Is that true?

Yes, it is the bare minimum period we require to be sure. Prime Minister Narendra Modi’s call for a 21-day nationwide shutdown is an effort to break the chain of transmission. India’s COVID-19 fight could make or break the global war. The “incubation period” means the time between catching the virus and beginning to have symptoms of the disease. Most estimates of the incubation period for COVID-19 range from 1-14 days.

A lockdown for 21 days would be a great social experiment which allows physical distancing. If followed strictly, it will contribute to delayed peak and to an extent, in flattening of the curve. Lockdowns may have to get extended in the areas with high transmission. It is important to identify such areas.

India has imposed the lockdown much earlier than many countries, including China, which failed to contain the initial spread of the virus. Although it started late, the Wuhan shutdown slowed the dispersal of infection to other cities by an estimated 2.91 days, delaying epidemic growth elsewhere in China. Other cities that implemented control measures pre-emptively reported 33.3% fewer cases in the first week of their outbreaks compared with cities that started control later.

Why were Wuhan and other cities under lockdown for two months?

In Wuhan, the measures started much later as compared to what India is doing. It takes that much longer when you start late. The initial outbreak of COVID-19 started in China and it was spread across before diagnoses and prreventive measures could be established. Not just China, by then the virus had spread to other countries as well.

As a result, longer lockdowns of nearly two months were required in some regions. Before the interventions, scientists estimated that each infected person passed on the coronavirus to more than two others, giving it the potential to spread rapidly. But between January 16 and 30, a period that included the first seven days of the lockdown, the virus reproduction decreased from 2.35 to 1.05. The number of new daily infections in China seems to have peaked on January 25 just two days after Wuhan was locked down.

Epidemiologists say that measures implemented during this time did work. But China’s mammoth response had one glaring flaw: it started too late. This delayed the measures to contain it.

In China, implementing the measures three weeks earlier, from the beginning of January, would have cut the number of infections to 5% of the total.

Will complete shutdown for 21 days alone be enough to break the chain? Is it right to say that shutdown only buys time?

It is right to say that shutdown not only buys time but also decreases the overall burden and delays the outbreaks in most places. Stronger containment measures done together with these mitigation measures will ensure flattening the epidemic.

Mitigation measures or shutdown alone are not enough to break the chain of emerging COVID-19 pandemic. The containment strategies include identifying all cases which are positive and identifying their contacts, too. Once identified, cases will have to be isolated, and contacts will have to be placed under quarantine.

Mitigation is a precursory measure and if containment is also not done, it is not going to help. Both need to go hand-in-hand.

Also, reviewing of States where any single case is confirmed is need of the hour. Contact tracing of all those people who might have got the infection is highly needed. Only then will India succeed in current strategies to combat COVID-19.

What then should be done during the lockdown?

Aggressive testing alone without mitigation doesn’t help in breaking the chain of transmission. Without mitigation, the spread of the infection from one person to another will happen at a faster rate. We may find a certain number of cases doubling every week, also the number of deaths. The lockdown is an opportunity for us to rapidly scale up the capacity to have enough resources to manage, isolate and provide intensive care for those who needed it. Both measures going hand-in-hand could have a reasonable effect on flattening the epidemic curve.

The revisions in testing strategy involving accredited private laboratories too could not solve the issue since only a particular number of suspected can be tested in a day. With its high population, testing everybody in India is out of the question. Therefore, we need to follow mitigation measures. I recommend the syndromic approach now, wherein we need to manage every case of fever, cough and respiratory distress as COVID-19 unless otherwise proved. Once testing is scaled up, this can get better.

Should India find all suspected cases in the community and test them, as per WHO’s recommendation?

This virus effectively hides and quickly doubles. By testing only suspect cases, we might miss many of those who are asymptomatic during screening. The best strategy is to test among the SARI (severely affected respiratory infections) admitted in the hospitals and the OPDs of these areas. Many States have not even begun testing such cases. This is part of March 23 national recommendations. Therefore, strong national and local surveillance review is needed. There is a potential to cause illness suddenly in large numbers of people. Without having an idea of the total number of cases, it would become guesswork to plan for the future management of COVID-19.

Can contact tracing, quarantining and testing of contacts of people who participated in the religious congregation in Nizammudin alone be sufficient?

Tracing such contacts, quarantining them and testing such cases are definitely most necessary but not sufficient by themselves. Wherever hot spots are present, stricter enforcement of lockdown, even beyond what is already announced is needed. There should be enforcement of active surveillance in these areas for any flu-like illness, and people should be encouraged to self-report. Other measures such as providing accurate information and building awareness in the hot spots, especially on personal hygiene, hand hygiene and cough etiquettes are necessary.

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Printable version | Jul 8, 2020 6:20:34 AM | https://www.thehindu.com/sci-tech/science/shutdown-alone-is-not-enough-to-break-the-chain/article31257261.ece

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