Omicron has driven Covid infections to record-breaking levels in a quarter of countries across the globe, new data show. 

In areas with high immunity levels, hospitals are coping, but in countries including the United States and India, there are signs that intensive care unit capacity could be overwhelmed. 

While data shows Omicron causes less severe illness when individuals have strong immunity, the sheer number of infections risks toppling healthcare systems across the world, according to Telegraph analysis of Our World in Data figures. 

Since the start of this year, new cases per million people have reached all-time highs in 46 of 191 countries – including the UK, France, Argentina and Mozambique – while global infections jumped by more than 70 per cent in the last week. Deaths are also beginning to rise in more than 80 countries. 

"While Omicron does appear to be less severe compared to Delta, especially in those vaccinated, it does not mean it should be categorised as mild," Dr Tedros Adhanom Ghebreyesus, head of the World Health Organisation, said on Thursday. 

"Just like previous variants, Omicron is hospitalising people and it's killing people. In fact, the tsunami of cases is so huge and quick that it is overwhelming health systems around the world." 

Already, deaths are beginning to increase in 82 countries – and fatalities have reached at least 50 per cent of the previous high in 39 places, including Cyprus and Australia. 

The good news is analysts say there has been a decoupling of infections, hospitalisations, intensive care admissions and deaths in many areas. 

"During all previous waves in all countries, those four metrics were basically synchronised (within a few weeks)," Edouard Mathieu, head of data at Our World in Data, told the Telegraph. "Now, due to both the characteristics of Omicron and good vaccination coverage in many countries, we're seeing a very different picture." 

Ghadeer Mahar grimaces as she is given a vaccination at a Covid-19 booster vaccination centre at Hampden Park vaccination centre in Glasgow, Scotland. Photo / AP 

In South Africa and the UK, where Omicron is now dominant, and where cases have risen to unprecedented levels, deaths remain at less than a 10th of recorded highs. In South Africa, intensive care admissions peaked at a fifth of previous waves. 

Similarly, experts in Portugal and Israel are optimistic that high vaccination and booster rates will continue to prevent any significant jump in fatalities – while cases have surged, ICU admissions are low and deaths stand at 5 and 1 per cent of the previous peak. 

The immunity wall 

But in countries with a low "immunity wall" the decoupling is less clear-cut. 

"The reality is that the variant will be different in different places, depending on the combination of vaccine and prior infection," said Dr Guy Harling, an epidemiologist at University College London's Institute for Global Health. 

In Mozambique – where cases have jumped more than 500 per cent since mid-December and the President and his wife are among those testing positive for coronavirus – deaths already stand at 31 per cent of the previous high, and are still rising rapidly. 

Ghana, Zimbabwe, the Ivory Coast and Angola are among other countries where deaths have surpassed 20 per cent of the previous peak and are still mounting. 

But while less than 10 per cent of the population have had two jabs, Harling said the young population and low testing rate could soften the Omicron blow – some of these countries may have greater levels of prior immunity from infection than recorded. 

Meanwhile, stringent border controls across Asia have kept Covid out for much of the pandemic, but this means prior immunity from previous waves is almost non-existent. 

Vaccinations have also lagged below 60 per cent in countries like Laos and Vietnam – which are both recovering from their largest waves to date, driven by Delta – and there are concerns that Chinese vaccines used widely in some nations offer far lower protection against Omicron. 

American hospitals under strain 

The result of different levels of immunity, mixed with ongoing struggles with the more intense Delta variant, means "decoupling" also differs across the western world. 

In much of the United States – where vaccination rates have stalled at roughly 60 per cent – hospitals and intensive care units are coming under mounting pressure. 

Registered nurse Morgan Flynn works inside a patient's room in the Covid-19 Intensive Care Unit at Dartmouth-Hitchcock Medical Centre, in Lebanon, New Hampshire. Photo / AP 

New admissions to ICU units are at or nearing record highs in places like Maryland and Washington DC, and are climbing fast in states including Massachusetts, Delaware and Virginia. 

As in the UK, elective surgeries are being postponed nationwide to free up medics and beds, as hospitals struggle with a triple whammy of high staff absences, severe cases and incidental infections. 

"The only time the US crossed 125,000 hospitalised Covid patients was January 5, 2020, when there were about zero vaccines," Dr Eric Topol, an American professor of molecular medicine, wrote on Twitter. "We're at about 126,000 (+6,000 from yesterday). Whatever 'decoupling' hoped for vs prior peak is quickly getting minimised." 

In New York City hospitalisations have also surpassed last winter's peak. Intensive care doctors say that although there aren't as many patients "gasping for air", incidental infections seem "to topple a delicate balance of an underlying illness" and are complicating care, while the sheer number of cases is overwhelming. 

However, Omicron has replaced the more severe Delta strain only recently. Estimates from the US Centre for Disease Control suggest that while Omicron is now responsible for 95 per cent of cases, the highly contagious variant only became dominant in late December. 

"Our oldest populations are not as heavily vaccinated or boosted as in the UK," Dr Natalie Dean, an assistant professor of biostatistics at Emory University in the US, told The Telegraph. "In some states like Massachusetts, death numbers have been ticking up – but there was already a background of a Delta surge". 

Canada, too, has reported more patients in hospital than ever before. There are currently 753 patients in ICU – well below the record high of 1469, but the latest wave is only just beginning. 

The recent Delta surge is also muddying the picture in European countries like Denmark and Switzerland, plus Australia – which has reported more cases since Christmas than during the rest of the pandemic combined. 

But in New South Wales, which has seen record-breaking hospitalisation rates, authorities say 74 per cent of Covid-positive patients admitted to intensive care units since December 16 are infected with Delta, not Omicron. 

"[There is] an odd situation where all conversations revolve around Omicron's lesser severity – as if it represented already 100 per cent of the infections," said Mr Mathieu. "Delta is still a big problem." 

Flying blind 

Elsewhere, scientists are largely flying blind. Experts are especially concerned about the potential impact of Omicron in countries including Bolivia, Argentina and the Philippines – where infections have risen by 955 per cent in the last week. 

In India, too, there is worry. The number of Covid patients needing oxygen in Delhi's intensive care units rose fivefold overnight on Wednesday. 

"We're seeing huge surges in cases in India... suggesting the immunity from the Delta wave isn't preventing reinfections and [is] leading to the rapid transmission across many of the cities," said Charlie Whittaker, from Imperial College London's department of Infectious Disease Epidemiology. "But it's less clear how that's going to affect disease severity." 

Across the border in Pakistan, experts fear they could be vulnerable to a severe wave. Cases are rising and the world's fifth most populous nation has not yet been hit by a severe wave. 

Syed Faisal Mahmood, an infectious disease consultant at Karachi's Aga Khan University, said Pakistan was potentially sitting on a "perfect storm". 

The nation's initial wave of vaccination was six months ago and few have been boosted. December is the traditional wedding season with large social gatherings and many travellers attending from abroad. 

"I think we are sitting in a place where we could potentially see a fairly large surge coming in," he said. 

- by Sarah Newey, Ben Butcher and Ben Farmer; Daily Telegraph UK