The World Health Organisation announced on Thursday that a million people had died from Covid-19 in 2022, calling it a "tragic milestone" when all the tools existed to prevent deaths.

Nearly 6.45 million deaths have been reported to the WHO since the virus was first detected in China in late 2019.

But WHO chief Tedros Adhanom Ghebreyesus questioned whether the world was really on top of the pandemic, this far in.

"This week, we crossed the tragic milestone of one million reported deaths so far this year," he told a press conference.

"We cannot say we are learning to live with Covid-19 when one million people have died with Covid-19 this year alone, when we are two-and-a-half years into the pandemic and have all the tools necessary to prevent these deaths.

"We ask all governments to strengthen their efforts to vaccinate all health workers, older people and others at the highest risk, on the way to 70 percent vaccine coverage for the whole population."

Tedros wanted all countries to have vaccinated 70 percent of their populations by the end of June.

But 136 countries failed to reach the target, of which 66 still had coverage below 40 percent.

"It is pleasing to see that some countries with the lowest vaccination rates are now making up ground, especially in Africa," Tedros said on Thursday.

He said only 10 countries had less than 10 percent coverage, most of which were facing humanitarian emergencies.

"However, much more needs to be done," said Tedros.

"One-third of the world's population remains unvaccinated, including two-thirds of health workers and three-quarters of older adults in low-income countries.

"All countries at all income levels must do more to vaccinate those most at risk, to ensure access to life-saving therapeutics, to continue testing and sequencing, and to set tailored, proportionate policies to limit transmission and save lives."

Derrick Sim of the Gavi vaccine alliance said a million deaths in 2022 was a million too many.

"Behind each statistic is a very real human tragedy, and as... the world deals with competing priorities, we cannot become numb to the toll the pandemic is having on individuals, families, and communities," he said.

More than 593 million cases have now been reported to the UN health agency. Despite testing rates having dropped sharply in many countries, around half of those cases were reported this year.

The Omicron variant accounted for 99 percent of virus samples collected in the last 30 days that have been sequenced and uploaded to the Gisaid global science initiative.

Of these, the BA.5 group of Omicron sub-variants remain globally dominant at 74 percent.

"There is increasing diversity within BA.5 descendent lineages, with additional mutations in the spike and non-spike regions," the WHO said. (AFP)