Post modeling scenarios say lockdown is necessary to defeat Covid infection
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Covid-19

Post modeling scenarios say lockdown is necessary to defeat Covid infection

Papiya Bhattacharya

Papiya Bhattacharya

The lockdown in India has been extended by another two weeks till May 17. What could the easing of restrictions lead to?

Post lockdown modeling scenarios in India predict rise in cases of Covid infection if normal life resumes while newer models and studies suggest newer strategies such as alternating lockdown days with normal days periodically to balance the economy as well as control the spread of the infection.

Researchers at the Indian Institute of Science (IISc) and Tata Institute of Fundamental Research (TIFR) have carried out city-scale simulation experiments and modeled the outcomes of post-lockdown scenarios. They have proposed three scenarios for large metro cities (Mumbai. and Bangalore) from agent based simulation model studies and drawn some useful information and strategies that can help policy makers review policies.

The first scenario is lifting the lockdown and letting people mingle with case isolations. If the lockdown was lifted and normal activity resumes, the number of direct COVID-19 fatalities might increase to levels under a no intervention scenario, but with some delay says the model. The second scenario is lifting fifty percent of the lockdown where half the workforce returns to offices and fifty percent of the restrictions stay in place. With phased reopening of offices, case isolations, home quarantine, isolation of those above 65 and closure of educational institutions, the model again predicts a rise in Covid cases. The third scenario is complete lockdown for an indefinite period. The model predicts a decrease in Covid deaths, in this scenario.

The researchers suggest that the studies could provide useful insights for public health officials and policymakers on decisions related to easing of restrictions and lockdown during the duration of the pandemic.

Prof Rajesh Sundaresan at the Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, is the corresponding author of the working paper written by the group of scientists from IISc and TIFR. He said of the study, “For what our model would predict for other cities, it depends on the

city's demographics. Our report merely provides a comparison of some identified interventions. There may be other intervention strategies (e.g., testing, cluster identification, case isolation, etc.) that could be combined with some of the interventions to get a more effective composite intervention.”

Dr Sandeep Juneja is Professor and Dean at the TIFR School of Technology and Computer Science in Mumbai. As one of the lead authors of the study he says that, “Lockdown buys the administration time to carry out aggressive measures to check infection spread - contact tracing, quarantining, cordoning off hot spots, etc. Without these measures stringently implemented, lockdown may simply lead to delay in the rise in infections. I think similar models have been developed in many parts of the world. There is nothing special about our model as such. We have worked hard to incorporate features somewhat unique to Indian cities; such as high density areas in Mumbai. Travel system used by most of the city. “

How would the modeling studies help policy makers in containing the cases? Dr Gagandeep Kang is Clinician Scientist, Fellow of the Royal Society and Executive Director of Translational Health Science and Technology Institute. She is also the vice-chair of the Coalition for Epidemic Preparedness Innovations (CEPI), a global alliance that has backed eight potential vaccines against the virus. She says about the study, “In terms of public health, I can say that there are no easy solutions. The model provided (and indeed, all models), show that the more the interventions and the longer they are implemented for, the fewer the number of cases and severe disease. Public health authorities in every country will have to play a balancing act between prevention of SARS-CoV2 spread, impact on healthcare systems to manage other diseases, the economy and societal structures.”

However, these modeling studies have not taken into account the economical or ethical aspects, caution the researchers.

Dr. T. Jacob John, eminent virologist and Emeritus Professor of Virology, Christian Medical College, Vellore has played a significant role in policy making in the eradication of polio in India. Dr John feels a lockdown is an extreme form of physical distancing and only if well planned military fashion to support families should lockdown be applied for more than one month.

He says, “I am happy that some serious attempt is made to bring science and modelling into the picture. The study shows clearly that any mitigation intervention, including lockdown for even long period, will only flatten the curve

and delay the peak, but once life is allowed back to normal (unlock), then the curve catches up with what would have been the original curve. During that interval with low number of cases we buy time to do other things -- like procure test kits, plan healthcare system well, procure PPE, ventilators etc.. Lockdown works in organised community living but not in slums. ”

Others are quick to point out the importance and help that the study can lend. Prof Gautam I. Menon, Departments of Physics and Biology, Ashoka University has been involved in similar modeling studies and his group at Ashoka is creating similar agent-based models at the full country level, in collaboration with a company called ThoughtWorks. They hope to be in a position to simulate around 5% of India's population using an agent-based model within a few weeks and then to get to about 40-50% in the months following. “These models approach the problem from different ends and make different assumptions, but the test will be to see if they replicate each other’s results in specific cases,” says Dr Menon. [See https://www.ashoka.edu.in/welcome/news#/post/ashoka-university-and-thoughtworks-to-build-simulation-model-to-track-covid19-spread-410]

On any other interventions that could be included in the study Dr Menon says, “In some work we have done recently, in a detailed epidemiological compartmental model called INDSCI-SIM, we emphasize the importance of a testing and quarantining regime that is made more rigorous in time as one way of ensuring that the epidemic growth is restricted. It would be nice to see if this could be replicated in a more detailed agent-based model. Deciding which parts of the population might be considered high-risk and targeting them would also be interesting to see being implemented”. [See https://indscicov.in/for-scientists-healthcare-professionals/mathematical-modelling/indscisim/].

Experts urge caution on the economic aspects. Dr Ashish Verma, associate professor at the Department of Civil Engineering in IISc, Bangalore feels that the results of the three scenarios are not surprising and are on expected lines.

On what could be the best scenario, he says, “If it is solely about controlling the COVID-19 spread and minimizing deaths due to it then clearly the third scenario is the best one. However, if it is also about balancing the economy i.e. minimizing the economic loss then the choice of best becomes complex. “

He adds, “While in lockdown, since there is hardly any traffic on the roads, the number of deaths due to road accident (about 400 persons die in India due to road accident everyday) must have been negligible during this period. Therefore, as a side positive effect, a number of lives have been saved in India during lockdown

from road accident deaths. Similarly, deaths due to other causes may also differ during the lockdown. When we look at the economic aspect, it is not only the industrial productivity, GDP etc. but also the economic cost of human life.”

Probable Remedies for the economical situation to improve

Dr Vishwesha Guttal is a mathematical ecologist at the Centre for Ecological Sciences in IISC, Bangalore. He is involved in another modeling project (https://indscicov.in/for-scientists-healthcare-professionals/mathematical-modelling/indscisim/) and suggests a lightswitch strategy, that is going back and forth between lockdowns and normal life.

He says, “Our work suggests the following, some of which overlaps with what Rajesh's team has found -

(a) A single lockdown of the duration of the current size (e.g. 40 days) only delays the epidemic.

(b) However, we need to complement this together with aggressive testing, case isolations and quarantining. These can be an effective way to control the epidemic, at least on a short term.

(c) As long as we have not yet reached herd immunity (for Covid, this could be around 60%) and when we release the lockdown, the next wave of the epidemic will invariably start after some time.

(d) Therefore, in our work, we consider periodic lockdowns -- where we periodically go back and forth between lockdowns and open days. We also consider a lightswitch strategy, where we go to lockdown when we begin to reach hospital capacity. These strategies allow open days which is important for livelihoods and economy.”

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