How well do China’s vaccines work against omicron?

With donations and sales, China made its covid shots accessible to the developing world even as the US and EU hoarded vaccines for their own populations. Days after the World Health Organization named omicron a variant of concern, leader Xi Jinping announced that China would be donating 1 billion doses of covid vaccines to Africa, the continent with the lowest vaccination rate.

According to Beijing-based Bridge Consulting, as of Dec. 27, China has sold 1.6 billion doses of vaccines to other countries, and donated another 133 million. With China’s population included, about 4.5 billion doses of Sinopharm and Sinovac’s CoronaVac have been supplied globally as of mid-December 2021.

But preliminary research suggests China’s vaccines are significantly less effective against omicron—even with a booster. Though the studies are small in scale and are not yet peer reviewed, they signal that countries that relied on these vaccines for their rollouts may need to consider pricier mRNA shots for further doses.

Sinovac’s efficacy against omicron

Even prior to omicron, Sinovac’s efficacy rates were lower than those of other vaccines, offering about 51% protection against symptomatic infection (though much better protection against severe disease).  In July, a study in Thailand found that antibodies from a double shot of the Sinovac vaccine halved every 40 days against the original covid strain.

Researchers at Hong Kong University found that two doses followed by a booster of Sinovac’s CoronaVac do not provide enough antibodies to neutralize omicron, though a booster of a Pfizer vaccine improved protection.

The finding has has implications for the biggest users of this vaccine, including Chile, the United Arab Emirates, and Indonesia, which suffered a severe covid wave in August. In July, Indonesia began administering Moderna boosters to medical professionals previously inoculated with Sinovac, after some became seriously ill or died from covid. (The country intends to begin a booster program for the wider public in January 2022.)

Sinopharm and omicron

Similarly, a booster may not make Sinopharm significantly more effective against omicron. Sinopharm has said its vaccine is 79% effective against symptomatic infection from the original covid strain.

A study (pdf) by Shanghai Jiao Tong University School of Medicine found that a booster shot of Sinopharm produced significantly lower antibodies against omicron, compared with the protection it provided for the variant discovered in Wuhan in early 2020.

Some countries, including Thailand and the Philippines, that had originally procured China-made vaccines started moving away from Sinovac and Sinopharm in mid-2021 after they were shown to be less effective during waves of the delta variant, in favor of the vaccines made by Pfizer and Moderna.