While we will never truly glimpse that sunnier reality, epidemiologists can statistically project just how much healthier the world might have been, were it not for the shadow of the coronavirus.

In a new study, scientists estimated the number of excess deaths due to the COVID-19 pandemic in 29 high-income countries – examining the historical trend of all-cause mortality in each nation over the last five years (2016–2020), and modeling how many deaths would have been expected if the pandemic hadn’t occurred.

The sole focus on high-income countries was due to where data came from: the Human Mortality Database, which collects comprehensive mortality and population data for member countries of the Organisation for Economic Cooperation and Development (OECD).

For the purposes of the study, only 29 OECD countries had reported complete data for the period – including the US, Israel, South Korea, New Zealand, and 25 European nations – so the researchers restricted their analysis to those places.

In that limited yet still vast subset of the world’s population, the COVID-19 pandemic took a grim toll. In total, almost 1 million excess deaths were attributed to the pandemic in the 29 countries, with an estimated 979,000 extra deaths occurring throughout 2020.

The US exhibited the highest absolute number of excess mortality with 458,000 extra deaths, followed by the UK (94,400), Italy (89,100), Spain (84,100), and Poland (60,100).

Proportionally speaking, however, the excess death toll tells a different story, divided amongst both men and women, with excess death rates significantly higher in men once age was accounted for.

The highest excess death rates (per 100,000 people) in men were in Lithuania (285), Poland (191), Spain (179), Hungary (174), and Italy (168), whereas the highest rates in women were in Lithuania (210), Spain (180), Hungary (169), Slovenia (158), and Belgium (151).

In both men and women, being older was linked with a higher excess death rate, with excess deaths particularly concentrated among people aged 75 or older, while excess deaths for young people aged 15 and under aligned more closely with expectations in most countries.

Not everywhere experienced the same surges in death throughout 2020, however.

In Norway and Denmark, observed deaths in 2020 were effectively on par with where historical trends projected they would be, suggesting the pandemic didn’t significantly affect overall mortality in the period.

And in one country, New Zealand, mortality actually fell below where it was expected to be, with the island nation experiencing approximately 2,500 fewer deaths than the modeling otherwise predicted for 2020.

While this result is certainly remarkable, it’s not altogether a surprise, having been found in previous mortality analyses by other researchers, and speaking to the success of New Zealand’s celebrated approach to virus containment and overall handling of the pandemic, aided by the significant geographical advantages of being a remote island country.

"New Zealand stood out as the only country that had a lower than expected mortality across all the age groups, in both men and women..." the researchers, led by epidemiologist Nazrul Islam from the University of Oxford, explain in their study.

As for how the pandemic could have seemingly saved lives in New Zealand – by reducing mortality in 2020 below expected levels – nobody really knows for sure, due to the observational nature of this kind of research.

But researchers have previously suggested that increased public health measures may have had a protective effect on the population, leading to significant drops in mortality from seasonal influenza and pneumonia, which in normal years cost many lives.

Elsewhere, things were not so fortunate, and in many places, the excess mortality effect of the pandemic went far beyond deaths that can directly be attributed to cases of COVID-19.

Some of those excess deaths could reflect under-reported coronavirus infections, but the researchers also say the indirect consequences of the pandemic likely cost many extra lives in 2020 – adverse health outcomes from living in the socially isolated circumstances of lockdown, or experiencing reduced access to medical care due to disrupted health systems, and other negative social or economic consequences arising from the crisis.

As bleak as the findings are, the researchers say this kind of as‌sessment helps us to understand the overall impact of the pandemic on human life – although it’s worth remembering, we’re halfway into 2021, and the event isn’t over yet.

"Its full impact may not be apparent for many years," a team of researchers from Imperial College London explain in a commentary on the new study.

"Particularly in lower income countries where factors such as poverty, lack of vaccines, weak health systems, and high population density place people at increased risk from COVID-19 and related harm."

The findings are reported in The BMJ.