A new paper published on the preprint server medRxiv* in April 2020 suggests, based on mathematical models, that premature removal of lockdown restrictions in India could be highly counterproductive, enhancing the secondary spread of COVID-19, pushing up the number of fatalities and prolonging the course of the pandemic in India.
New Delhi, India - March 16, 2020, People wearing masks due to Covid-19 virus outbreak in India. Image Credit: Deepak Bhoj / Shutterstock
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
How India’s lockdown began
In January 2020, when the news of a few cases of viral pneumonic illness in an obscure Chinese city appeared in the papers, few in India could have foreseen the course of the next few months. Progressing from a solitary case in Kerala, at India’s southern tip, on January 30, 2020, the virus has inexorably taken its toll, affecting over 46,000 people in different states, with almost 1,500 deaths as of May 5, 2020.
When the World Health Organization (WHO) declared the novel coronavirus outbreak to be a pandemic on March 11, 2020, it also appealed to the world to take preventive measures to diagnose active cases, isolate them with their primary contacts, and ensure timely treatment of severe infection.
In India, the first case was a student who had returned from Wuhan. A returnee from Italy followed this, and then an Italian tourist party with their guide was detected to be positive in Rajasthan. Subsequently, the number of cases went up all over India, though gradually as first, as is the want of this virus.
Maharashtra and New Delhi had the highest number of cases as of March 14, at 14 and 7 cases, respectively. Currently, the totals here are almost 12,300 and 4,100, respectively, but Gujarat has overtaken Delhi with over 5,000 cases at present.
As the virus tore through Wuhan and the surrounding regions of China, leaving its trail of disease and death, the government of India announced a series of rapid-fire restrictions.
These began with shutting down international flights, quickly progressed through social distancing measures, and shutting down all public transport (buses, trains, and flights) to the declaration of a lockdown at the national level on March 24, 2020.
Why India needed a lockdown
The rationale behind such comprehensive and apparently impulsive moves is simple: India has a massive population of 1.35 billion, with inadequate tertiary healthcare coverage and limited infrastructural health resources. This leaves it open to a much higher risk of rapid and overwhelming spread of the infection than most other developed countries.
The government of India needs the full cooperation of its people, therefore, to contain the community spread of the virus, by informing them of the real risks of the situation and securing their willing compliance with quarantine and social distancing measures. These are aimed at slowing person-to-person spread.
AMRAVATI, MH, INDIA 22 MARCH 2020: Parked trains at Amravati railway station during curfew imposed as a preventive measure against the COVID-19, Appeal of Prime Minister Indi. Image Credit: CRS PHOTO / Shutterstock
How was the current study done?
The current study is an epidemiological attempt to model the outcome of these measures using the right mathematical models. Existing research suggests that pandemics typically show an exponential pattern of growth at the beginning, but then flatten out.
In this study, the different models used by researchers to predict how the case infection rate increases are evaluated.
Exponential phase
In the first phase, the exponential model is useful as it reflects the spread of the virus, using a J-shaped curve. This model does not predict the downward phase or decay of the curve and the plateau phase.
The current phase of the pandemic in India, according to this study, is the second phase, where exponential growth has given way to steady growth. This type of increase in cases cannot, therefore, be predicted by the exponential model.
Logistic model
This model predicts the course of disease spread in the presence of constraints, such as the restrictions placed on the mobility of people, medical facilities dedicated to the care of COVID-19 patients, and total lockdown conditions. This leads to a change in the number of people classified as susceptible to infection because of the isolation imposed under these conditions. The change in the number of infected people is calculated correspondingly.
SEIR Model
SEIR refers to the adaptation of a popular paradigm used to predict the growth of a population or the spread of a disease, namely, ‘Susceptible-Infectious-Removed’ (SIR). In pandemics, this is modified; namely, the ‘Susceptible-Exposed-Infectious-Removed’ (SEIR) model, to ensure greater accuracy since it includes a lot of factors that influence the growth rate due to the virus spread.
Taking into account the actions taken by the government to limit the spread, the researchers have come up with an equation to predict the outcome in terms of the caseload.
The number of confirmed cases was obtained from the Ministry of Health and Family Welfare (MOHFW) and COVID-19 websites, beginning from March 5, 2020, which marked the first day of the lockdown, to April 23, 2020. The researchers then projected the pattern of spread over the next 42 days, beginning from the end of the second phase of the lockdown, that is, May 2, 2020, to June 14, 2020, adjusting for the impact of government interventions.
The 42-day period was divided into three cycles, lasting 14 days each, representing one incubation period each.
What are the study results?
With the end of the second phase of the lockdown on May 2, the government needs to consider two different modes of action. First, it has to continue to promote social distancing and isolation to keep the pandemic toll at bay. Secondly, it has to take measures to revive the economy after a prolonged period of recession. Thus, unless due consideration is given, India may head towards disaster, both in terms of health and financial management.
Using data from the earliest days from the imposition of lockdown in India, the researchers looked at the impact of this measure on the rate of disease transmission as reflected in the number of cases.
Using a linear growth model, the researchers projected their estimate of the number of cases and fatalities at present. Once the lockdown is lifted, the other two scenarios will come into play. One is based on an optimistic view of the virus spread, the other pessimistic.
Optimistic vs. pessimistic outlook
With the optimistic view, the researchers predict that the virus spread will continue as at present, with new cases appearing every day, to peak in the second week of May. After this point, the curve points downward to touch rock bottom on June 14, 2020, with about 40 new cases being reported daily. According to this scenario, India’s COVID-19 scenario will end in the third week of June 2020, has affected about 78,000 people. The fatalities will touch about 2,440.
With the pessimistic scenario, the outbreak will follow the worst possible pattern. The total number of cases will continue to go up until the middle of June 2020, with daily new cases peaking in the last week of May 2020.
The total number of cases will cross 208,000 at this point, with about 283,000 people being infected as of June 14, 2020. After that, the growth of the pandemic will slow down slowly, over another 4-5 weeks, to end in the second week of July 2020. Overall, about 10,200 people will die.
What are the options?
- Healthwise, complete lockdown for a period of 70 days, or 10 weeks, will be the best option to achieve a near-complete control of viral spread in India. They quote Richard Horton, editor-in-chief of The Lancet, as commenting that lifting the lockdown on May 3 will be a grave error, triggering the second wave of the pandemic. In fact, this will make the earlier investment and efforts a fruitless exercise. The model in view here is the 10-week lockdown of Wuhan, which resulted in the successful containment of the virus.
- A second option is to continue the lockdown for 70 days while allowing essential activities to resume after May 3. This is still a potential cause of spreading infection, first among essential workers and then to their contacts or to people near them. This situation, therefore, places the onus of watchfulness on the government to prevent an outbreak.
- Lift the lockdown – this will be a serious error, making contact tracing impossible and leading to a situation where the number of cases is so high as to overwhelm the pathetic healthcare situation in India at large. Compared to developed countries such as the USA, the UK, Spain, Italy, and France, the COVID-19 infection rate has not really taken off until now. The researchers attribute this slow rate of increase to the firm government action in limiting social interactions between people not from the same household.
The way forward
The reasonable conclusion is that India is not ready to have the lockdown lifted, at least in states with ongoing active infection. Restrictions on travel are essential in this fight to avoid the rapid spread of readily transmissible viruses like SARS-CoV-2, even assuming no local transmission is occurring.
Even as lockdown measures continue, quarantine should be enforced by the authorities, along with the appropriate treatment of the sick, to mitigate the pandemic in India.
Complete lockdown should always be accompanied by random testing on a mass scale along with the testing of suspects. Contacts must be aggressively traced to catch the scale of secondary spread. This is where a strict lockdown is useful to break the chain of transmission.
The model is limited by its failure to take into consideration several vital measures and parameters such as the health status of the patient, relative immune status of various population groups, passive immunization, temperature, population density, and demographic factors.
The researchers quote virologist Ian Lipkin as advising the twin strategies of aggressive testing and isolation of hotspots (clusters of infection). If these are put in place, the government may allow relaxation of the lockdown to pursue essential activities, especially concerning livelihood activities. With such a balanced plan in place, the government may be able to bring about a moderate measure of control of the spread of the virus, while facilitating economic recovery over the long term.
*Important notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
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