What is SUTRA Model? Know all about India’s fight with second Covid wave

SUTRA Model: Why in News?

SUTRA standing for Susceptible, Undetected, Tested (positive) and Removed Approach earlier gained a public eye when one of its expert members informed in October 2020 that India had crossed the COVID 19 peak.  The prediction for the second wave, however failed and the rising number of cases are a standing proof of the same. 

What is SUTRA?

National COVID 19 Supermodel Committee was formed by the Government of India to make projections about the spread of COVID 19 in India and help in making short and long term plans to defend the country from the dangerous disease caused due to the virus. The committee, however, accepted that it was unable to predict the exact nature of the second Covid wave in the country. 

The panel was working on the SUTRA model for calculating the trajectory of the disease in India. This committee comprises three scientists namely, Manindra Agrawal, Professor, IIT Kanpur, Madhuri Kanitkar, Deputy Chief, Integrated Defense Staff and M Vidyasagar, Professor, IIT Hyderabad who work on this model. 

SUTRA: Reason for miscalculation

1. The panel said that their predictions were wrong as the nature of the virus has been changing constantly and very rapidly. 

2. As per the committee," In such a context, any prediction for Covid-19 must be continually readjusted, sometimes almost daily."

3. Various epidemiological models extrapolate cases on the basis of 

1. Data of the existing cases
2. Behaviour of the virus
3. The way of its spread

However, the SUTRA model chose a data centric approach. 

4. The equation to find out the estimates of future infections and the timing of a peak occurring, require certain ‘constants’. Such numbers on the other hand kept changing and their values depended on the number of infections reported at various intervals.

5. So any equation cannot make it clear when a constant changes. An increase in the number of cases thus couldn’t be predicted in advance.

6. Others are of the view that SUTRA relied on many parameters and recalibrated them when its predictions broke down. 

7. Also many scientists are of the view that the exponential rise was not calculated as there was a contact between people and populations went wrong every time. 

8. It was assumed that the best it could do was go upto the pre lockdown values. No one thought about the new strains that could come up with time. 

9. The model also relied on the ICMR in May that said that 0.73% of India may have been infected at that time. However, the results of the first survey had not been correct. 

The game-changer

The SUTRA model has been undermined due to the following reasons

1. Omission of the importance of the changing behaviour of the virus 
2. Observations informing that some people were bigger transmitters of the virus than others Lack of accounting for social or geographic heterogeneity 
3. Non-stratification of the population by age ( contacts between different age groups were not accounted for)

Way Forward:

The new variants have been put up in the SUTRA model as an increase in value of parameters called beta.  As per the scientists now “the model is observing changes in parameter values. It does not care about what is the reason behind the change. And computing new beta value is good enough for the model to predict the new trajectory well.” Due to the combination of epidemiologists, data-centric modelling such as SUTRA and time-series models can work to their best. 

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