So how can we quantify the costs and benefits of one of the largest public health interventions ever? 

"This is a very difficult calculation to make," Sarah Burgard, a sociologist at the University of Michigan, told AFP. 

According to official counts, the virus has infected at least 7.4 million people around the world and more than 415,000 have died.

Burgard said in the end it may prove difficult to untangle how many deaths were caused by COVID-19 and how many by "the chaos and fallout" of the crisis. 

"I don't have a lot of faith that we are going to be able to come up with a very clear number," she said. 

Even if a figure is reached, decisions over its implications would be "heavily political and ethically complex".

The response to the disease had led to an unprecedented reorganization of societies, with businesses shuttered, stay-at-home orders, medical facilities refocused on treating COVID-19 patients.

The economic impact of the measures has caused alarm and division.

 

'Unknown situation' 

In a study published in 2000, the American economist Christopher Ruhm asked a provocative question: "Are recessions good for your health?"

His research found that a rise in unemployment sharpened stresses on mental health, causing increases in substance abuse and suicide. 

But there were unexpected benefits for physical health: road accidents and pollution reduced, while people had more time for exercise.   

Reflecting on his work two decades later, Ruhm said that in a normal economic slump "when unemployment was high, mortality was low and vice versa". 

But the coronavirus-induced recession is not a normal economic downturn. 

"We are in an unknown situation," Ruhm said in an April online talk for the University of Virginia, where he is a professor of public policy and economics.

"I think it may be the first time in history that we are actually deliberately creating a recession, not because we want to create a recession, but because this health threat is so real."

 

No silver linings 

Now societies are bearing the strain of both a deadly pandemic and a huge economic shock.

The virus undercuts the usual "silver linings" of an economic downturn, said Burgard. 

Populations have been confined inside, reducing access to beneficial physical exercise.

People struggling with bereavement, mental health issues or unemployment find it harder to access their normal support networks, with even visits to family members restricted.   

And the healthcare sector itself has been battered by the virus, with frontline staff at risk of infection while treatments for other illnesses have been postponed.

Even in normal times, any positive effects seen in economic downturns are often in richer nations. 

"The opposite seems true in many low- and middle-income countries, where mortality actually increases during recession," said Thomas Hone, a public health researcher at Imperial College London. 

He said this may suggest that what protects people from the harms of recessions are "strong health systems and social security nets".

Many fear the scale of the pandemic and economic downturn will disproportionately hurt the most vulnerable.

UN agencies and the vaccine alliance Gavi have said virus restrictions caused immunizations to be disrupted in nearly 70 countries, affecting some 80 million children under the age of one and threatening a resurgence of preventable diseases like polio and measles.

The World Food Program estimates the number of people facing acute hunger this year could nearly double -- to 265 million. 

 

'No choice'

Will the long-term ramifications of lockdowns counteract the effect they had on slowing contagion? 

In a study published on Monday, Imperial College researchers estimated that lockdowns had prevented around 3.1 million deaths in 11 European countries. 

On Wednesday, Imperial epidemiologist Neil Ferguson told a British parliamentary committee that because of the exponential spread of the virus, locking down just a week earlier would have reduced the final death toll by "at least a half". 

But any modeling is based on assumptions -- in this case calculations of what would have happened if action had not been taken. 

Restrictions were imposed after predictions of potentially enormous tolls, said Arthur Caplan, professor of bioethics at New York University.

"I don't think politicians and leaders had a choice," he said. 

"If you saw those numbers in the millions of deaths, you had to take steps because you would have had a broken health system, a public that wouldn't have come out anyway because they would have been terrified."

Caplan said there should be a "broad set of voices" in determining whether the lockdowns were the right solution, but added that the question would be "political".