We, the scientists working on the SUTRA model for charting the trajectory of COVID-19, would like to clearly point out some facts related to predictions of our mathematical model, especially since some of these have been misunderstood and misquoted. Recent reports in some media seem to suggest that scientists working on the SUTRA model cautioned in March about the second wave but attention was not paid to it. This is incorrect. 
A meeting was called on 2nd April to seek our inputs by one of the very senior officers of the government coordinating the national pandemic response. We indicated that the SUTRA model predicted the second wave to peak by the third week of April and to stay most likely around 1 lakh daily cases.  Clearly the model predictions in this instance were incorrect because of the reasons below.
We have been working on a mathematical model to predict the spread of the virus. It is important to note that a mathematical model can only predict future with some certainty so long as virus dynamics and its transmissibility don’t change substantially over time. Mathematical models can also provide a mechanism to predicting alternate scenarios corresponding to various policy decisions such as non-pharmaceutical interventions.
In the case of COVID-19, it is clear that the nature of the virus has been changing very rapidly. In such a context, any prediction for COVID-19 must be continually readjusted, sometimes almost daily.
We are working closely with the government and our inputs have always been received positively. While we could not predict the exact nature of the second wave earlier, we continue our efforts to better estimate its future trajectory.
Manindra Agrawal, Professor, IIT Kanpur
Madhuri Kanitkar, Deputy Chief, Integrated Defense Staff
M Vidyasagar, Professor, IIT Hyderabad

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       RP/ (IIT Kanpur)