The head of the World Health Organization said a close to 90% decline in COVID deaths globally compared to nine months ago is “cause for optimism,” but urged leaders to remain vigilant as new variants continue to emerge.

Tedros Adhanom Ghebreyesus told reporters on Wednesday that there were just 9,400 COVID deaths last week, compared with more than 75,000 in February, the Associated Press reported. 

“Almost 10,000 deaths a week is 10,000 too many for a disease that can be prevented and treated,” he said.

Testing and sequencing rates remain low globally, vaccination gaps between rich and poor countries are still wide, and new variants continue to proliferate.

In its weekly epidemiological update, the agency said the global tally of cases fell 15% in the week through Nov. 6 from the previous week with over 2.1 million new cases counted.

The highest number of new cases was reported from Japan, at 401,693, followed by Korea at 299,440 and the U.S. at 266,104. The agency again cautioned that the numbers may be undercounted, given the changes in testing strategies and overall surveillance in many countries, including the U.S.

As for new variants, the update found BA.5, an omicron subvariant, remained dominant globally, accounting for 74.5% of sequences submitted to a central database. But newer ones, including BQ.1 and XBB, are on the rise.

BQ.1 sequences rose to 13.4% of the total from 9.4% a week ago. XBB rose to 2.0% from 1.1%. The WHO is still closely monitoring newer sublineages but called on countries to also track them closely.

In the U.S., known cases of COVID are climbing again for the first time in a few months. The daily average for new cases stood at 40,189 on Wednesday, according to a New York Times tracker, up 7% versus two weeks ago.

Cases are rising extremely sharply in some states, led by Nevada, where they are up 96% from two weeks ago. New Mexico’s case tally has climbed 64% from two weeks ago and Utah is up 61%. Overall, cases are rising in 32 states and are flat in Delaware. They are also rising in Washington, D.C., Guam, Puerto Rico and the U.S. Virgin Islands.

The daily average for hospitalizations was up 3% at 28,003, while the daily average for deaths is down 13% to 316.

Coronavirus Update: MarketWatch’s daily roundup has been curating and reporting all the latest developments every weekday since the coronavirus pandemic began

Other COVID-19 news you should know about:

• China’s new top leadership body reaffirmed Beijing’s “dynamic-zero” COVID-19 policy on Thursday, as case numbers rose and authorities in the city of Guangzhou urged residents to work from home but stopped short of a citywide lockdown, Reuters reported. In its first meeting since being formed last month after the ruling Communist Party’s twice-a-decade congress, the Politburo Standing Committee said China’s epidemic prevention measures must not be relaxed, according to state media.

• AstraZeneca PLC on Thursday lifted its guidance for the full year after reporting a swing to net profit and higher sales for the third quarter of the year, which both beat consensus expectations, Dow Jones Newswires reported. The Anglo-Swedish drug company dropped its submission for U.S. regulatory approval for its COVID vaccine, saying it has decided to focus instead on areas with greater unmet medical needs. The vaccine was initially approved in the U.K. and Europe about two years ago. CEO Pascal Soriot said the submission in the U.S. was becoming “very complicated and very large,” as it had to gather data from around the world.

• Pfizer PFE, +1.09% and German partner BioNTech BNTX, -3.95% said Thursday that their booster dose of the omicron BA.4/BA.5-adapted bivalent COVID vaccine for 5-to-11 year olds was recommended for marketing authorization in the European Union. The EU will review the recommendation from the European Medicines Agency (EMA) Committee for Medicinal Products for Human Use (CHMP), and is expected to make a decision “soon.” The companies’ bivalent booster is already authorized in the EU for people at least 12 years old.

Here’s what the numbers say:

The global tally of confirmed cases of COVID-19 topped 633.9 million on Monday, while the death toll rose above 6.60 million, according to data aggregated by Johns Hopkins University.

The U.S. leads the world with 97.9 million cases and 1,073,934 fatalities.

The Centers for Disease Control and Prevention’s tracker shows that 227.3 million people living in the U.S., equal to 68.5% of the total population, are fully vaccinated, meaning they have had their primary shots.

So far, just 26.3 million Americans have had the updated COVID booster that targets the original virus and the omicron variants, equal to 8.4% of the overall population.