Maybe data astronomy: Indian experts question study predicting fourth wave of Covid in June

New Delhi:

Forecasting models are only good for short-term projections and an IIT-Kanpur study predicting a fourth wave of Covid in India in June could be ‘data astronomy’ and guesswork at best, say several scientists .

Allaying fears of a new spike in cases in the next three months, they also took note that most Indians have received two vaccines and one natural infection. So even if there is a wave, the consequences in terms of hospitalizations and deaths should be manageable unless there is a new variant.

“Active cases are declining quite rapidly – and looking at current trends, we certainly can’t say anything about a new surge in the future,” said Sithabra Sinha, a professor at the Chennai Institute of Mathematical Sciences (IMSc). .

The reproductive number (R) – the expected number of cases directly generated by a case in a population – for India is at the lowest value since COVID-19 broke out here in March 2020, he said. added.

According to the recent modeling study conducted by researchers from Indian Institute of Technology-Kanpur, the fourth wave of the Covid pandemic in India may start around June 22 and peak around mid-to-late August.

The yet-to-be-peer-reviewed study, published on preprint repository MedRxiv, used a statistical model to make the prediction, concluding that the possible new wave will last for four months.

Research conducted by Sabara Parshad Rajeshbhai, Subhra Sankar Dhar and Shalabh of IIT Kanpur, also noted that there is always a good chance that a possible new variant of the coronavirus will have an intense impact on the whole of the world. to analyse.

The study generated a lively debate with experts questioning the assumptions made in it.

The precise timing itself is suspect, said Gautam Menon, who has been tracking India’s Covid numbers since the start of the pandemic. The methodology, in his view, is questionable and any modeling exercise that forecasts months ahead is unreliable.

“I would not trust such a prediction, especially a prediction with specific dates and times,” the professor from the departments of physics and biology at Ashoka University in Haryana told PTI.

“We cannot predict anything about the future as the new variant that might arrive is unknown. What we can do however is be vigilant and collect the data that allows us to react quickly and effectively,” he said. he adds.

Public health expert Bhramar Mukherjee agreed, saying the type of prediction made in the IIT Kanpur article is akin to data astrology, not data science.

“I don’t believe in the former. In my experience, forecasting models are very good with a short-term forecast two to four weeks ahead,” said Mukherjee, professor of global public health at the University of Michigan, US, at PTI.

“Long-term forecasts are unreliable. Could anyone predict Omicron during Diwali? We should have some humility of knowledge based on the past,” added the scientist.

Theoretical physicist Sinha echoed the views of others.

“I would in any case be quite skeptical of such long-term predictions. Given the large number of uncertainties involved, any statement about what will happen in a few months is nothing better than mere guesswork. ” In the opinion of epidemiologist Ramanan Laxminarayan, there are likely to be new, smaller waves of the pandemic, but the basis for IIT Kanpur’s prediction is unclear.

“Emergence of new variants, continued vaccine coverage and possibly a booster policy will determine when and how COVID-19 reappears,” said Laxminarayan, director of the Center for Disease Dynamics, Economics & Policy in Washington and New Delhi. . PTI.

It is feared that a future outbreak could be caused by the highly contagious subavirus Omicron BA.2, spreading rapidly in many countries, including Denmark and the UK, or a brand new variant that could surprise the world like Omicron did it last November. .

“Already there is a high level of hybrid immunity, coming from a combination of previous infections and vaccinations. The Omicron wave was largely blunted because of this hybrid immunity, but also because this variant was less virulent in whole,” Menon said.

Laxminarayan added that there is a risk of future increases. Experience from other countries shows that the third wave of mutants in India was not because Omicron was much less virulent, but because the Indians were immune through previous exposure and vaccination.

“We need to pay attention to the data, focus on reopening schools and workplaces, continue vaccination efforts, stock up on antivirals and treatments, and increase mitigation strategies when we see an uptick. just like we did for the Omicron wave,” Mukherjee agrees.

Defending their study, authors Rajeshbhai, Sankar Dhar and Shalabh said that the scientific calculations used in the article are based on certain statistical models and scientific assumptions. The use of such models and assumptions is common in academia and research, they told PTI in a joint email.

“We have attempted to make predictions using statistical modeling which we believe could work in such scenarios. In research, we are always trying to solve an unknown problem based on a scientific framework,” the statement said.

“But often multiple assumptions are needed for the statistical inferences drawn. However, no one can guarantee success beyond a certain level of confidence, as there may be several factors that may influence the prediction which are mentioned in the preprint of the article,” the authors added.

The authors also noted that any statistical estimate is associated with variability.

“We are in the process of addressing the confidence measure of the start and end dates of the fourth wave, i.e. the next wave could start on June 22 more or less a few days,” they said. added.

According to Union Health Ministry figures on Saturday, 5,921 people tested positive for the infection in one day, taking India’s caseload to 4, 29, 57,477 (42.9 million/4 .29 crore). Active cases were 63,878.

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