The number of new COVID-19 cases reported worldwide rose for the fifth week in a row, largely driven by the hugely infectious Omicron subvariants BA.4 and BA.5, the World Health Organization (WHO) reported Thursday.

In its weekly COVID-19 review, the UN health agency said there were 5.7 million new infections last week, marking a 6-percent increase. There were 9,800 deaths, roughly similar to the previous week's figure.

Earlier this week, WHO Director-General Tedros Adhanom Ghebreyesus said the pandemic still qualifies as a global emergency and he was "concerned" about the recent spike.

"The virus is running freely, and countries are not effectively managing the disease burden," he said during a Tuesday press briefing. "New waves of the virus demonstrate again that COVID-19 is nowhere near over."

New cases surged by 30 percent in last two weeks

In the last two weeks, COVID-19 infections reported to the WHO surged by 30 percent, mainly driven by the Omicron BA.4 and BA.5. The two Omicron subvariants have shown a worrisome ability to re-infect people previously vaccinated or who have recovered from COVID-19.

According to the WHO, the biggest increases in COVID-19 cases were seen in the Western Pacific and the Middle East, where they jumped by more than a quarter. Deaths spiked by 78 percent in the Middle East and by 23 percent in Southeast Asia, while dropping elsewhere or remaining stable.

Relaxed policies complicate situation

The WHO said that relaxed COVID-19 surveillance and testing programs in numerous countries have complicated efforts to track the virus and catch potentially dangerous new variants.

In the U.S., the new Omicron variants have pushed up hospitalizations and deaths in recent weeks, prompting some cities and states to rethink their approaches. The White House COVID-19 coordinator Dr. Ashish Jha, during a Wednesday TV appearance, called for booster shots and renewed vigilance against the virus.

The White House response team has also urged all adults 50 and older to urgently get a booster if they haven't yet this year, and dissuaded people from waiting for the next generation of shots expected in the fall.

(With input from AP)