Explainer: Why are health experts still in a fix regarding coronavirus deaths?

With global deaths from the contagious coronavirus reaching one million, the health professionals are still striving to figure out a crucial metric in the pandemic: the fatality rate - the percentage of people infected with the pathogen who die.

Deaths from coronavirus-related illnesses have doubled from half a million in just three months, led by fatalities in the United States, Brazil, and India.

More than 5,400 people are dying around the world every 24 hours, according to Reuters calculations based on average deaths so far in September.

That equates to around 226 people per hour, or one person every 16 seconds. In the time it takes to watch a 90-minute soccer match, 340 people die on average.

The United States, Brazil, and India account for nearly 45% of all COVID-19 deaths globally, with the Latin American region alone responsible for more than a third of them.

India is the latest epicenter of the pandemic globally, recording the highest daily growth in infections in the world in recent weeks, with an average of about 87,500 new cases each day since the start of September.

On current trends, India will overtake the United States as the country with the most confirmed COVID-19 cases by the end of the year, even as Prime Minister Narendra Modi’s government pushes ahead with easing lockdown measures in a bid to jumpstart the struggling economy.

Despite the surge in cases, India’s death toll of around 95,500 and pace of growth of fatalities remain below those of the United States, Britain, and Brazil.

Health experts stress that official data for both deaths and cases globally since the first reported case in China in early January is almost certainly being underreported, especially in countries with limited testing capacity.

The reported global death rate has picked up from three months ago when an average of around 4,700 people were dying COVID-19 linked illness every 24 hours, or one person every 18 seconds.

Read more: Worldwide coronavirus death toll surpasses one million

Infection numbers are rising again in the United States and setting new records in Europe, which accounts for nearly 25% of deaths. The World Health Organisation (WHO) has warned of a worrying spread in western Europe just weeks away from the winter influenza season.

The WHO has also warned the pandemic still needs major control interventions amid rising case numbers in Latin America, where many countries have started to resume normal social and public life.

Much of Asia is experiencing a relative lull after emerging from a second wave. In Australia, officials have lifted some reimposed internal travel curbs.