The China Centers for Disease Control's director said Saturday authorities are considering mixing COVID-19 vaccines because the country's domestically made doses "don't have very high protection rates," per AP.

Why it matters: The remarks by the Gao Fu at a news conference in the southwestern city of Chengdumark mark the first time a Chinese health official has spoken publicly about the low efficacy of vaccines made in China.

• China has sent millions of doses of its coronavirus vaccine around the world.

Driving the news: Gao said officials were looking at two options designed "to solve the problem that the efficacy of ... existing vaccines is not high," according to the South China Morning Post.

• One is mixing vaccine, known as "sequential immunization," and the other is to "adjust the dosage, the interval between doses or increase the number of doses," the SCMP reports.  

The intrigue: Experts say the mixing of vaccines may "boost effectiveness rates," AP notes.

• Scientists in the United Kingdom are conducting clinical study into the mixing of the Oxford University-AstraZeneca and Pfizer-BioNTech COVID-19 vaccines.

The big picture: China's government has only approved locally made vaccines for use against the virus.

• Sinopharm announced just before its coronavirus vaccine was approved for use late last year that its vaccine was 79.3% effective, though experts said important data was missing.
• China's health regulator approved Sinovac's vaccine last February. Several phase 3 trials in Brazil, Turkey and Indonesia have shown efficacy rates between 50.38% to 91.25%, Axios' Shawna Chen notes.

Of note: Gao said "everyone should consider the benefits" of mRNA vaccines, used by Western drug makers as a tool against the pandemic but not by their counterparts in China, AP reports.

What they're saying: Tao Lina, a Shanghai-based vaccine expert who attended Gao's news conference, told the SCMP the "levels of antibodies generated by our vaccines are lower than mRNA vaccines and the efficacy data are also lower."

• It's a "natural conclusion that our inactivated vaccines and adenovirus vectored vaccines are less effective than mRNA vaccines," he added.

By the numbers: Gao said about 34 million people had received "both of the two doses required by Chinese vaccines and about 65 million received one," according to AP.

Go deeper: China and Russia vaccinate the world

Editor's note: This article has been updated with new details throughout.