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Scientists see flaws in SUTRA Model

Topics Covered: Issues related to health.

Scientists see flaws in SUTRA Model:


Context:

Questions are being raised by many scientists on whether a government-backed model, called SUTRA, to forecast the rise and ebb of the COVID-19 pandemic, may have had an outsized role in creating the perception that a catastrophic second wave was unlikely in India.

What is SUTRA model?

SUTRA (Susceptible, Undetected, Tested (positive), and Removed Approach) first came into public attention when one of its expert members announced in October that India was “past its peak”.

The model uses three main parameters to predict the course of the pandemic which are:

  1. Beta: Also called contact rate, which measures how many people an infected person infects per day. It is related to the R0 value, which is the number of people an infected person spreads the virus to over the course of their infection.
  2. Reach: It is a measure of the exposure level of the population to the pandemic.
  3. Epsilon: It is the ratio of detected and undetected cases.

Why questions are being raised now?

  1. Incorrect prediction: The model said a “second wave” would peak by the third week of April and stay around 1 lakh cases.
  2. Too many parameters: The SUTRA model was problematic as it relied on too many parameters, and recalibrated those parameters whenever its predictions “broke down”.
  3. Omission of the importance of the behaviour of the virus.
  4. The fact that some people were bigger transmitters of the virus than others (say a barber or a receptionist more than someone who worked from home).
  5. A lack of accounting for social or geographic heterogeneity.
  6. Not stratifying the population by age as it didn’t account for contacts between different age groups also undermined its validity.

InstaLinks:

Prelims Link and Mains Link:

Features and issues surrounding SUTRA Model.

Sources: the Hindu.