ANALYSIS: The coronavirus pandemic is extracting a heavy toll on Italy, with hospitals overwhelmed and a nationwide lockdown imposed.

But experts are also concerned about a seemingly high death rate, with the number of fatalities now outstripping the total reported in China.

Of 41,035 people confirmed coronavirus patients in Italy, 3405 so far have died – an increase of 427 in the last 24 hours.

By contrast, China has almost twice as many cases, 81,155, but 3245 fatalities.

In very crude terms, this means that around eight per cent of confirmed coronavirus patients have died in Italy, compared with four per cent in China.

READ MORE:

* Italy overtakes China's death toll

* Kiwi expat's life in quarantine in Italy

* Italy's death toll jumps 475 in a day

* Coronavirus pandemic: full coverage

By this measure Germany, which has so far identified 13,000 cases and 42 deaths, has a fatality rate of just 0.3 per cent.

AP Italy has become the country with the most coronavirus-related deaths, surpassing China with 3405 recorded fatalities.

So why the disparity?

According to Professor Walter Ricciardi, who is the scientific adviser to Roberto Speranza, Italy's minister of health, the country's mortality rate is far higher due to demographics – the nation has the second-oldest population worldwide after Japan – and the manner in which hospitals record deaths.

"The age of our patients in hospitals is substantially older – the median is 67, while in China it was 46," Prof Ricciardi says.

"So essentially the age distribution of our patients is substantially squeezed to an older age and this is substantial in increasing the lethality."

A study in the Journal of the American Medical Association this week found that almost 40 per cent of infections and 87 per cent of deaths in the country have been in patients aged over 70. According to modelling, the majority of this age group are likely to need critical hospital care – including 80 per cent of 80-somethings – putting immense pressure on the health system.

But Prof Ricciardi added that Italy's death rate may appear higher because of how doctors record fatalities.

"The way in which we code deaths in our country is very generous in the sense that all the people who die in hospitals with the coronavirus are deemed to be dying of the coronavirus.

"On re-evaluation by the National Institute of Health, only 12 per cent of death certificates have shown a direct causality from coronavirus, while 88 per cent of patients who have died have at least one pre-morbidity – many had two or three," he says.

Other experts have also expressed scepticism about the available data.

Martin McKee, professor of European public health at the London School of Hygiene and Tropical Medicine, says that countries do not yet have a good indication of how many mild infections they have.

But if further testing finds more asymptomatic cases spreading undetected, the mortality rate will drop.

"It's too early to make a comparison across Europe," he says. "We do not have detailed serosurveillance [blood serum monitoring] of the population and we do not know how many asymptomatic people are spreading it."

Prof McKee adds that testing was not consistent across the continent.

"In Germany, epidemiological surveillance is more challenging – simply because of the complexity of working in a federal state and because public health is organised very much at the local level."

But there are other factors that may have contributed to Italy's fatality rates, experts say, including a high rate of smoking and pollution – the majority of deaths have been in the northern Lombardy region, which is notorious for dirty air.

And there's also no question that parts of Italy's health system have been overwhelmed with a surge of coronavirus patients and are struggling to cope.

"Doctors in Italy haven't been dealing with one or two patients in care, but up to 1,200," says Dr Mike Ryan, health emergencies programme executive director at the World Health Organisation.

"The fact they're saving so many is a small miracle in itself."

This pressure is likely to get worse as more healthcare workers are infected and have to isolate – already, 2000 have contracted the virus.

"Based on Italy's experience, there is a real concern for the UK," adds Prof McKee. "Compared to almost every other European country, we have a relative shortage of ventilators and medical staff."