Among countries with both high vaccination rates and high rates of Covid-19 infection, most rely on vaccines made in China, a CNBC analysis shows.

The findings come as the efficacy of Chinese vaccines faces growing scrutiny, compounded by a lack of data on their protection against the more transmissible delta variant. CNBC found that weekly Covid cases, adjusted for population, have remained elevated in at least six of the world’s most inoculated countries — and five of them rely on vaccines from China.

CNBC identified 36 countries with more than 1,000 weekly new confirmed cases per million people as of July 6, using figures from Our World in Data, which compiles information from sources including the World Health Organization, governments and researchers at the University of Oxford. CNBC then identified countries among those 36 where more than 60% of the population has received at least one dose of Covid vaccine.

Those countries numbered six, and five of them use Chinese vaccines as a significant part of their national inoculation programs: United Arab Emirates, Seychelles, Mongolia, Uruguay and Chile. The one country among them that doesn’t depend on Chinese vaccines is the United Kingdom.

Mongolian state-owned news agency Montsame reported in May that the country has received 2.3 million doses of vaccine by China’s state-owned Sinopharm. That far exceeds the 80,000 doses of Russia’s Sputnik V and around 255,000 doses of Pfizer-BioNTech shot that Mongolia received as of last week.

Chile administered 16.8 million doses of vaccines from Beijing-based Sinovac Biotech — compared with 3.9 million doses of Pfizer-BioNTech and smaller amounts of two other vaccines, Reuters reported last month.

The UAE and Seychelles depended heavily on the Sinopharm vaccine at beginning of their inoculation campaigns, but each has more recently introduced other vaccines. In Uruguay, Sinovac’s shot is one of the two most-used vaccines, alongside Pfizer-BioNTech’s.

Meanwhile, the United Kingdom has approved vaccines by Moderna, AstraZeneca-Oxford, Pfizer-BioNTech and Janssen. U.K. Covid cases have spiked in recent weeks as the more transmissible delta variant has spread there.

Sinopharm and Sinovac did not respond to CNBC requests for comment.

Several factors can cause a surge in Covid cases in countries with high vaccination rates. Vaccines don’t offer 100% protection, so those who are inoculated can still be infected. At the same time, new variants of the coronavirus could prove better at overcoming vaccines.

The best option for many countries
Countries should not stop using Covid-19 vaccines from China, epidemiologists say, especially while the supply of vaccines is limited among low- and middle-income nations.

Many of the countries and territories that approved vaccines by Sinopharm and Sinovac are developing nations that can’t compete with wealthier countries for vaccines developed in the United States and Europe.
There’s ‘incredible inequity’ as many countries face Covid vaccine shortage
Ben Cowling, a professor at The University of Hong Kong’s School of Public Health, said countries may decide to use certain vaccines depending on their long-term objectives.

“Some countries may accept a low level of circulation as long as there are relatively few severe cases and deaths from COVID-19,” Cowling, who heads the school’s epidemiology and biostatistics division, told CNBC in an email. “That should be achievable with high coverage of any of the available vaccines.”

Still, some countries are steering clear of China’s vaccines. Costa Rica last month rejected a delivery of vaccines developed by Sinovac after concluding it isn’t effective enough.

WHO approval
The World Health Organization approved vaccines from Sinopharm and Sinovac for emergency use.

The effectiveness of the two Chinese vaccines is lower than that of Pfizer-BioNTech and Moderna, both of which have shown more than 90% efficacy.

Sinopharm’s vaccine has an efficacy of 79% against symptomatic Covid infections, the WHO says, but its effectiveness among certain groups — such as people 60 and older — isn’t clear. The efficacy of Sinovac’s shot has come in at around 50% to higher than 80%, depending on the country where trials were held.