The official global death toll from COVID-19 is on the verge of eclipsing six million - underscoring that the pandemic, now in its third year, is far from over.

The milestone is the latest tragic reminder of the unrelenting nature of the pandemic even as people are shedding masks, travel is resuming and businesses are reopening around the world.

The death toll, compiled by Johns Hopkins University, stood at 5,996,882 as of Sunday morning and was expected to pass the six million mark later in the day.

Remote Pacific islands are just now grappling with their first outbreaks and deaths, fuelled by the Omicron variant.

Hong Kong, which is registering a surge in deaths, is testing its entire population of 7.5 million three times this month as it clings to mainland China's "zero-COVID" strategy.

As death rates remain high in Poland, Hungary, Romania and other eastern European countries, the region has had more than one million refugees arrive from war-torn Ukraine, a country with poor vaccination coverage and high rates of cases and deaths.

And despite its wealth and vaccine availability, the United States is nearing one million reported deaths on its own.

It took the world seven months to record its first million deaths from the virus after the pandemic began in early 2020.

Four months later another million people had died, and one million have died every three months since, until the death toll hit five million at the end of October.

Now it has reached six million - more than the populations of Berlin and Brussels combined.

But despite the enormity of the figure, the world undoubtedly hit its six millionth death some time ago.

Poor record-keeping and testing in many parts of the world has led to an undercount in coronavirus deaths, in addition to excess deaths related to the pandemic but not from actual COVID-19 infections, like people who died from preventable causes but could not receive treatment because hospitals were full.

Edouard Mathieu, head of data for the Our World in Data portal, said that - when countries' excess mortality figures are studied - as many as nearly four times the reported death toll have likely died because of the pandemic.

An analysis of excess deaths by a team at The Economist estimates that the number of COVID-19 deaths is between 14 million and 23.5 million.

The US has the biggest official death toll in the world but the numbers have been trending downward over the last month.

The world has recorded more than 445 million confirmed COVID-19 cases and new weekly cases have been declining recently in all regions except for the Western Pacific, which includes China, Japan and South Korea, the World Health Organisation reported this week.

Although the overall figures in the Pacific islands having their first outbreaks are small compared to larger countries, they are significant among their tiny populations and threaten to overwhelm fragile health care systems.

"Given what we know about COVID ... it's likely to hit them for the next year or so at least," said Katie Greenwood, head of the Red Cross Pacific delegation.

Tonga reported its first outbreak after the virus arrived with international aid vessels following the January 15 eruption of a massive volcano followed by a tsunami.

It now has several hundred cases but - with 66 per cent of its population fully vaccinated - it has so far reported people suffering mostly mild symptoms and no deaths.

The Solomon Islands had its first outbreak in January and now has thousands of cases and more than 100 deaths.

In India, where the world was shocked by images of open-air pyres of bodies burned as crematoria were overwhelmed, the scars are fading as the number of new cases and deaths has slowed.

India has recorded more than 500,000 deaths but experts believe its true toll is in the millions, primarily from the Delta variant.

In the UK, infections have fallen since an Omicron-driven surge in December but remain high.

England has lifted all restrictions, including mask mandates and the requirement that all who test positive isolate at home.