India on Thursday recorded another 3,645 Covid-19 deaths, a new record for the country and a spike of over 350 from the previous day, according to health ministry data. 

The country, which is experiencing a relentless new wave of infections, has now seen 204,832 deaths in total from the coronavirus pandemic. 

US sends $100m Covid supplies

The United States said Wednesday it was sending more than $100 million in supplies to Covid-ravaged India, including nearly one million instant tests on a first flight.

The White House said the first flight would arrive Thursday in New Delhi on a military plane, days after President Joe Biden promised to step up assistance to the emerging US ally.

The first shipment includes 960,000 rapid tests, which can detect Covid in 15 minutes, and 100,000 N95 masks for frontline health workers, the US Agency for International Development said.

The White House said total aid on flights in the coming days would be worth more than $100 million and include 1,000 refillable oxygen cylinders and 1,700 concentrators that produce oxygen for patients from the air.

"Just as India sent assistance to the United States when our hospitals were strained early in the pandemic, the United States is determined to help India in its time of need," a White House statement said.

The White House said it was also sending supplies to India to produce more than 20 million vaccine doses.

The supplies are being diverted from US orders to produce the AstraZeneca vaccine, which has not been approved for use in the United States.

The White House had promised Sunday to free up material to let India produce Covishield, its low-cost version of AstraZeneca, after criticism that the United States was hogging supply even as it succeeds with mass vaccination.

Biden said Monday that the United States would also ship overseas up to 60 million AstraZeneca vaccine doses that have already been manufactured, but it remained unclear how many would go to India.

Nations have rushed supplies to India as it contends with one of the world's most catastrophic surges of Covid-19 since the pandemic began, overwhelming hospitals and pushing crematoriums past capacity.

The devastation comes even though India is a leading producer of vaccines. 

Why is there a deadly crunch?
A devastating surge in coronavirus infections has exposed India's dilapidated health infrastructure and a deep shortage of oxygen -- a key treatment for seriously ill Covid-19 patients.

AFP looks at the reasons behind the shortage:

- Why is medical oxygen vital? -
Oxygen therapy is crucial for severe Covid-19 patients with hypoxaemia -- when oxygen levels in the blood are too low.

"Some clinical studies show that up to a quarter of hospitalised (Covid-19) patients require oxygen therapy and upwards to two-thirds of those in intensive care units," community health specialist Rajib Dasgupta told AFP.

"This is why it is imperative to fix oxygen supply systems in hospital settings as this is a disease that affects lungs primarily."

Experts have long raised the alarm about shortages of medical oxygen in India and other poor countries to treat pneumonia, the world's biggest preventable infectious killer of children under five.

But the government has for years failed to invest enough money into such infrastructure, experts say.

- Does India produce enough oxygen? -
The short answer: yes.

Experts say the vast nation of 1.3 billion people is producing enough oxygen -- just over 7,000 tonnes a day. Most is for industrial use, but can be diverted for medical purposes.

The bottlenecks are in transport and storage.

Liquid oxygen at very low temperatures has to be transported in cryogenic tankers to distributors, which then convert it into gas for filling cylinders.

But India is short of cryogenic tankers.

And such special tankers, when filled, have to be transported by road and not by air for safety reasons.

Most oxygen producers are in India's east, while the soaring demand has been in cities including financial hub Mumbai in the west and the capital Delhi in the north.

"The supply chain has to be tweaked to move medical oxygen from certain regions which have excess supply to regions which need more supply," the head of one of India's biggest medical oxygen suppliers Inox Air Products, Siddharth Jain, told AFP.

Meanwhile, many hospitals do not have on-site oxygen plants, often because of poor infrastructure, a lack of expertise and high costs.

Late last year, India issued tenders for on-site oxygen plants for hospitals. But the plans were never actioned, local media report.

- What's being done? -
The government is importing mobile oxygen generation plants and tankers, building more than 500 new plants and buying portable oxygen concentrators.

Industries have been ordered by the government not to use liquid oxygen.

Oxygen supplies are being brought to hard-hit regions using special train services.

The military has also been mobilised to transport tankers and other supplies domestically and from international sources.

Emergency medical supplies -- including liquid oxygen, cryogenic tankers, concentrators and ventilators -- are being flown in from other countries in a huge aid effort.

- What's happening on the ground? -
Oxygen shortages are still affecting badly hit regions despite the measures to boost supply, transport and storage.

Reports have emerged of hospitals asking patients to arrange for their own cylinders and of people dying even after being admitted due to low oxygen supplies.

Social media platforms have been filled with posts by desperate families hunting for cylinders and refills.

Meanwhile, there is a growing black market for cylinders and concentrators sold far above their usual retail prices.

The shortages have sparked outrage and frustration in Delhi.

"The government did not plan in time," sales executive Prabhat Kumar told AFP.

"Had it been prepared, we would not have to suffer like this for beds and oxygen."