## When Will COVID Third Wave Arrive ?

The burning question right now is – when will the third wave hit us and at what intensity? Many leading scientists and researchers are carrying out their own calculations about how third wave will affect us.

Recently, a very credible model has surfaced on the internet which gives you the estimated time and what intensity the third wave is going to hit us? The model is known as SUTRA. The acronym stands for SUSCEPTIBLE, UNDETECTED, TESTED(positive), REMOVED APPROACH. This mathematical model was developed by M. AGARWAL(IIT KANPUR) , M. KANITKAR (INTEGRATED DEFENSE STAFF) and M. VIDYASAGAR(IIT HYDERABAD).

You can check this link and dive into the intricacies of the model:-

A presentation is available on model at

Now, why this model is credible? That is because this group of IIT professors and a defense staff actually got their previous two models bang on. They used the same  numerically stable methods for estimating the infection rates in the last two waves and it actually fit right in. So, now that they have come up with yet another eagerly anticipated prediction, everyone is interested to know more about the model.

First, let’s try and understand how did they derive this mathematical method or formula, if we can say that. Their method is based on 4 key factors :-

• The “R” factor which is the reproductive rate. It basically tells you at what rate the virus is going to multiply and thus, how infectious can it be!
• The second factor is the vaccination numbers. India has an ambitious target of getting all the adults vaccinated by the end of this year.
• The third and most important factor is the reinfection chances of those who got themselves jabbed at the early stage of vaccination drive. We have already seen numerous graphs and statistical report of pre-vaccination stage, now, what everyone is anticipated about is the post-vaccination scenario. Whether  or not, the vaccine is effective enough.
• The fourth and perhaps the most unpredictable factor is the arrival of new highly infectious variant into the scene. In the previous model, they displayed the reasons why did we witness such massive number of cases per day; it was because of the unlock stage, elections, covid inappropriate behavior and also because of the new variant.

These are the four basic factors on which the model is currently based on.

Now that we have gathered the basics of this model, we can move forward to what actually this model have predicted?

The SUTRA model states that the third wave is a unique scenario where they had to study serum positivity, whether or not non-vaccinated masses have antibodies, among many parameters.

So, keeping in mind all these ifs and buts, they have come to three possible outcomes. Let us discuss them broadly.

The first possible outcome is the optimistic one. In the first outcome, they say about where life goes back to normal and there is no new variants that hover over us, which, if I may, is overly optimistic. The predicted peak that a single day can witness will vary between 50,000- 1,00,000 new cases. Given, we continue the vaccination drive vigorously and the masses across the country actually get vaccinated and continue to follow covid protocols, such as, maintaining social distancing, wearing double masks, etc.

It is very likely that we will not witness major mass gathering that happened last time due to elections and kumbh mela. Basically, this outcome do not take into account any major virus spreader events as such and very optimistically predict the scenario.

Next, let’s see the intermediate outcome, in which they considered somehow the efficiency of vaccine showed a decline of 15-20%. The chances of appearance of new variant is completely ruled out.

Even in the absence of new variant, and minimized effectiveness of the vaccine, we should witness the daily peak of about 1,50,000 – 2,00,000 without any major changes.

The last but not the least, is the pessimistic outcome. Here, the chances of appearances of new variant which is 25% more infectious is taken into consideration, which I think is inevitable. Also, the vaccination drive is carried out how it is being done presently, very ambitiously!

Ruling out the variables and constants in this method, they made this prediction that even in pessimistic outcome, the peak will vary between 1,50,000- 2,00,000 cases per day.

These are the three scenarios talking about the intensity of the third wave. But when will the third wave hit us?

Let’s cut the chase.

The researchers are telling us the peak of third wave will arrive somewhere between mid-October to mid-November, somehow telling us that just around Diwali we are going to see the third wave of covid-19.

A model is just a map, simple and easy to understand and far from intricacies of the world. So unless the assumptions of model face abrupt changes, the model can guess the trajectory pretty well. But you never know, with so many unknowns. You can still think of having a model better than not having one.