Photo by Isi Parente on Unsplash

On April 11, 2020, Press Information Bureau of India tweeted this projection data of #COVID-19 in the absence of lockdown.

Let’s critically analyze this.

Most of the #COVID19 predictions are based on the following Susceptible-Exposed-Infectious-Recovered (SEIR) predictive modelling published by CoronaTracker on WHO:

At the start of the paper, it says this: COVID-19 is still an unclear infectious disease, which means we can only obtain an accurate SEIR prediction AFTER the outbreak ends. But in any case, let’s keep analysing this.

In SIER, individuals are each assigned to one of the following disease states.

Note: β, controls the rate of spread, which represents the probability of transmitting disease between a susceptible and an infectious individual. And this is UNKNOWN to any of us at this moment.

β is so hard to determine that it requires even analysing each and every piece of news to see how the model gets affected by the sentiment of each news. If the β is unknown, and you just base the β based on past data, the model gets flawed at the beginning itself.

But let’s assume (big assumption here!) that the exposed people were coming only from China on 20th January and let’s try to create a model for this. This is how a model of India looks like as if today.

COVID-19 Projection Data for India

Note the number of deaths is spot on in this simulation (242 deaths as if today vs 250 shown in the graph).

So why is total infectious 261,000? Because it’s a simulation with a scenario that everyone comes out to be #COVID19 positive if they fall in the model.

However, In India, only 4.67% of people are found to be infected in these tests as of 10 April, 9:00 PM IST. So by that percentage, we would have only 12,188 cases as if today if there were no lockdown but containment measures.

However, let’s say there were no containment measures also. In that case, we will have to look at the global percentage and see what’s the upper bound. 17% of people are found to be infected in tests done by Italy (highest in the world). If that is the probable percentage, we would have 44,370 people infected as if today (without any lockdown). So the number of 2,08,544 cases as if today is just over-estimated.

Few places you can check this model are:

https://covid19-scenarios.org

http://covid19forecast.science.unimelb.edu.au/#10-day-forecast

https://alhill.shinyapps.io/COVID19seir/