The UN health agency has "continued to urge China" to share more rapid, regular, reliable data on hospitalisations and deaths, as well as more comprehensive, real-time viral sequencing in the wake of a Covid surge in the East Asian country.

"The World Health Organization (WHO) is concerned about the risk to life in the world's most populous country and reiterated the importance of stepping up vaccination coverage, including booster doses," WHO Director-General Tedros Adhanom Ghebreyesus said recently in his first online briefing for the year.

"With circulation in China so high and comprehensive data not forthcoming – as I said last week it is understandable that some countries are taking steps they believe will protect their citizens," he added.

Several countries, including the US, have announced new Covid testing requirements for travellers from China to gain domestic entry, amid concerns over the spread of the latest variants.

WHO Emergencies Director Dr Mike Ryan said: "We know there are difficulties in all countries very often in recording hospital releases, admissions and use of ICU (intensive care unit) facilities."

"We believe that the current numbers being published from China underrepresents the true impact of the disease in terms of hospital admissions, in terms of ICU admissions, and particularly in terms of deaths."

Also Read: Is China sharing enough COVID-19 information?

WHO has held high-level meetings with Chinese authorities over the past week to discuss the rise in cases and hospitalisations.

The UN agency's Technical Advisory Group on Virus Evolution (TAG-VE) also met with Chinese experts to discuss the situation.

During that meeting, scientists from the Chinese Center for Disease Control and Prevention presented data from what they described as imported and locally acquired coronavirus infections.

The analysis showed that most of the viruses circulating in the country are of two Omicron lineages, BA.5.2 and BF.7, which accounted for 97.5 percent of all local infections, as well as a few other known Omicron sublineages.

"These variants are known and have been circulating in other countries, and at present no new variant has been reported by the China CDC," the TAG-VE said in a statement on Wednesday.

So far, 773 sequences from mainland China have been submitted to the virus database operated by the global science initiative, GISAID.

Most, 564, were collected after December 1. Of this number, only 95 are labelled as locally acquired cases, while 187 are imported and 261 "do not have this information provided."

The majority of the locally acquired cases, 95 percent, belong to the two Omicron lineages.

"This is in line with genomes from travellers from China submitted to the GISAID EpiCoV database by other countries. No new variant or mutation of known significance is noted in the publicly available sequence data," the statement said.

Tedros said the pandemic is now in its fourth year, and despite progress, it is still a threat to health, economies, and societies.

"We are really concerned about the current Covid-19 epidemiological picture, with both intense transmission in several parts of the world and a recombinant sub-variant spreading quickly," he said.

Covid was on the decline for most of 2021, Tedros added, citing factors such as increased vaccinations worldwide and the identification of new lifesaving antivirals.

However, there are still major inequities in access to testing, treatment and vaccination.

"Every week, approximately 10,000 people die of Covid-19, that we are aware of. The true toll is likely much higher," he said.

Also, the Omicron subvariant XBB.1.5 is on the rise in the US and Europe and has been identified in nearly 30 countries.

XBB.1.5 was initially detected in October 2022.  It is the most transmissible subvariant yet, according to Dr Maria Van Kherkove, the WHO technical lead for Covid.

"We do expect further waves of infection around the world, but that doesn't have to translate into further waves of death because our countermeasures continue to work," she said.

Meanwhile, the TAG-VE experts are also working on a related risk assessment that should be published in the coming days.  

Dr Van Kherkove emphasised the importance of continued Covid surveillance around the world to track known subvariants that are in circulation.

Last month, more than 13 million cases of the disease were reported, though the WHO believes the toll is higher.

"But more concerning, we've had a 15 percent increase in deaths in the last month and again, we know that that is an underestimate because there are delays in reporting, and with the holiday period and with mixing, those trends are expected to continue," Dr Van Kherkove said.