The BA.2 Omicron subvariant, also known as “stealth Omicron” is pushing cases up in the country, in part because of the population’s lack of widespread natural immunity Gottlieb told CNBC’s Squawk Box. 

“China has a population that’s very vulnerable to this new variant. This is a much more contagious variant, it’s going to be harder to control, and they don’t have a population that has natural immunity,” Gottlieb told CNBC.

Although Gottlieb didn’t say it directly, his comments suggest that the zero-COVID policy that was so successful over the last two years in limiting COVID cases also had a hand in creating this extreme vulnerability.

China’s largest-ever COVID numbers

The world’s second-largest economy is recording its largest ever numbers of COVID since the start of the pandemic. The country recorded an average of 1,477 cases per day last week, according to The New York Times, and cases have increased by 377% from the average two weeks ago.

On March 15, China issued city-wide lockdowns in place in Shenzhen, affecting 12.5 million people, Dongguan (10.5 million), and Langfang (5.5 million), and locked down the whole province of Jilin, affecting 24 million. That’s 52.5 million people

In Shanghai, schools have returned to online classes and on Saturday city officials told residents not to leave unless absolutely necessary, meaning tens of millions more were in quasi-lockdown as well. 

COVID cases are rising in some parts of the world as countries relax previous COVID restrictions and the highly contagious subvariant spreads. In Europe, the U.K., France, and Italy among other countries have seen their infection numbers increase. Yet, the World Health Organization said in February that a previous Omicron infection provides some immunity against the BA.2 subvariant. 

Lessons for the world

The lockdown in Shenzhen, which is supposed to last a week, will have a ripple effect on the production of cars, electronics, and notably Apple products, some of which are produced there by the company’s supplier, Foxconn. 

The lockdowns and resulting production halts are necessary under China’s zero-COVID policy, which includes strict quarantines and travel restrictions. But, according to Gottlieb—who serves on the board of COVID vaccine maker Pfizer—the renewed spread is due in part to the limited effectiveness of the vaccines China has deployed against the BA.2 omicron subvariant.

“They didn’t use the time that they bought themselves to really put in place measures that would prevent omicron from spreading,” he said to CNBC.

When it comes to the West and the U.S., though, Gottlieb said they likely won’t share China’s fate. Although Western countries faced higher case numbers because they didn’t implement COVID restrictions as restrictive as China’s, they seem to be less vulnerable to this new subvariant.

Gottlieb said that in the next couple weeks, COVID cases will likely rise in the rest of the world as restrictions are pulled back and the more contagious Omicron subvariant spreads among the population. Yet, unlike China, a combination of immunity due to previous COVID-19 spread in the U.S. and protection by vaccines could that increase to be brief. 

“It’s going to cause a lot of anxiety as you start to see cases tick up,” he said. “There’s going to be a lot of people who are worried this is the beginning of another surge, but given how much infection we’ve had, given how vaccinated we are, I think that’s going to be a pretty good backstop against uncontrolled spread here.”