The variant from India is perhaps the most contagious coronavirus mutation on the planet, according to Tom Wenseleers, an evolutionary biologist at the University of Leuven in Belgium.

Wenseleers was the first scientist to claim that the UK variant was more transmissible than other versions of the virus, a claim first disputed but later affirmed by other experts.

"The new variant from India has a very big transmission or growth advantage," even over the UK mutation, he said in an interview with an American radio network, NPR. "It's kind of like the UK variant squared."

Wenseleers told NPR that this advantage was fueling the massive outbreak in India, on top of other contributing factors, such as recent mass gatherings, election rallies and relaxing of precautions.

The NPR report noted that over the winter, the situation in India looked normal: Covid-19 case numbers were flat and even dropping.

Then in the middle of February and early March, the situation quickly shifted. The virus surged explosively. Now India is battling a horrific second wave of Covid-19, reporting about 400,000 cases and more than 4,000 deaths every day.

Dr Roderico H. Ofrin, the World Health Organisation's (WHO) representative to India, however, puts more blame on India's failure to follow standard operating procedures (SOPs). "We saw that people were not behaving in a way that was appropriate to slowing Covid-19, and I think that's why we are where we are," he said. "There are many reasons, but basically, we gave the virus a chance to keep transmitting."

'No model to predict virus spread'

Dr Yasmin Ali Haque, the Unicef representative in India, said in the same UN report that it would take years to overcome the consequences of this pandemic.

"We are already seeing the secondary effects, especially on children and the poorest and most marginalised groups," she said.

Read: Pleas for help in India as Covid-19 leaves children without carers

Dr Haque pointed out that only about 50 per cent of children in India have access to remote learning. That means that around 150 million children of school-going age did not have access. "We are already hearing of stories of an increase in child labour, the early marriage of girls especially and even child trafficking."

The UN report warned that the current test positivity rate in India, 19pc, was too high. It noted that the infection pattern in India was similar to what was seen in Europe or the United States, but the scale was very different.

Acknowledging that the density of the population was probably also a factor, the report identified that matching the scale of the surge with the scale of the response was the real problem.

"This virus is adapting so fast, that no model has been able to predict how it will spread," it warned. "We have to be ahead of the game: it's a cycle of preparedness, readiness, response, and recovery. You can't stop."

But the report also noted that India has vast experience of mass vaccination and it would learn to meet this enormous challenge as well.

'Virus surge threatens to reverse gains'

Another UN report warned that the "deadly new surge in South Asia threatens to reverse global gains against the Covid-19 pandemic and have disproportionate impact on children."

The report — which includes inputs by the Unicef and WHO — noted that countries across South Asia were witnessing rises in infections, with India accounting for over 90pc of both infections and deaths in the region.

Pakistan was also experiencing a major surge in Covid-19 and the number of cases increased rapidly in recent weeks, with daily cases reaching a seven-day average of 5,500 cases per day, up from an average of 1,100 cases per day in February, the report added.

A humanitarian bulletin from the UN Office for the Coordination of Humanitarian Affairs (OCHA) noted that the pandemic had impacted the healthcare system in Punjab and Khyber Pakhtunkhwa, with hospitals reporting shortages of available beds, oxygen, and other essential supplies.

"The scenes we are witnessing in South Asia are unlike anything our region has seen before," said George Laryea-Adjei, Uniced Regional Director for South Asia. "We are faced with a real possibility that our health systems will be strained to a breaking point — leading to even more loss of life."

Worsening situation in S. Asia

According to the WHO, India accounted for 46pc of global cases and 25pc of global deaths reported in the past week. Maldives, Nepal, and Sri Lanka also reported increasing caseloads.

The report depicted the situation in Nepal as particularly alarming, with a 137pc rise in infections this week. It is the highest since the pandemic started last year. The hike has severely strained its fragile health system, resulting in a shortage of hospital beds, intensive care units, and critical medical supplies, including personal protective equipment (PPE) and oxygen concentrators.

The Nepalese government last week announced a lockdown in many locations across the country, including in Kathmandu valley, and suspended domestic flights to stymie the spread of coronavirus.

Across South Asia, “family members of patients are pleading for help as the region reels under an acute shortage of medical-grade oxygen. Exhausted health workers are being pushed to the brink of collapse,” warned the Unicef report.

“Urgent action and steadfast leadership are indispensable to stopping the catastrophe. Governments must do everything within their power to stop the devastation, and partners that are able to send assistance must do so immediately."

Urging the international community to "step up without delay," Unicef added: “This is not just a moral imperative. The deadly new surge in South Asia threatens us all. It has the potential to reverse hard-earned global gains against the pandemic if not halted as soon as possible."

The statement also underlined the need for enforcing precautionary measures across the region: "Now more than ever, we must commit ourselves to wearing masks, handwashing with soap as often as possible, keeping physical distance and getting ourselves vaccinated if we have the opportunity to do so."

Unicef noted that "very low levels of vaccination" in South Asia magnify the likelihood of the virus spiraling even further out of control, noting that in almost all countries in the region, except for Maldives and Bhutan, fewer than 1 in 10 people have been vaccinated.

"Now more than ever, we must ensure vaccines equitably reach all populations. Manufacturing must be ramped up, technology transferred, and doses equitably shared. None of us are safe until all of us are safe."