2 Doses of China’s Sinovac Vaccines Ineffective Against Omicron: Hong Kong Study

By Nicole Hao
Nicole Hao
Nicole Hao
Nicole Hao is a Washington-based reporter focused on China-related topics. Before joining the Epoch Media Group in July 2009, she worked as a global product manager for a railway business in Paris, France.
December 16, 2021 Updated: December 16, 2021

A new study found that two doses of China’s Sinovac COVID-19 vaccine didn’t generate appreciable numbers of antibodies against the new, highly infectious, omicron variant.

The study tested the blood from 25 people who were fully vaccinated with Sinovac’s Coronavac. None of them “contain sufficient antibodies to neutralize the Omicron variant,” researchers at the Department of Microbiology of the University of Hong Kong (HKU) wrote in their statement released on Dec. 14. The study used two Omicron variants, one from South Africa and one from Nigeria.

The HKU’s study was accepted for publication in the medical journal “Clinical Infectious Diseases” and released online as a preprint.

However, Sinovac didn’t agree with the study and published its own test results on Dec. 15. Sinovac claimed that it obtained two Omicron variants from HKU, and used one of them for the testing.

“35 percent (seven samples) of the serum of the 20 Coronavac vaccine recipients, who had two shots, have neutralizing antibodies [against Omicron],” Sinovac stated without elaborating on details.

Sean Lin, Ph.D. and former virology lab director at Walter Reed Army Hospital, told The Epoch Times on Dec. 15 that the HKU study is trustworthy, not only because it was led by Kwok-Yung Yuen, a highly respected professor in infectious diseases, but also because the study’s results match other studies published in medical journals in recent months.

“HKU’s study tested several variants on the serums, not only omicron. From the study, we can find that the antibodies in the serums aren’t reduced, but don’t have enough effect when facing the omicron variant. … To Coronavac vaccine recipients, the antibodies that their bodies generated after vaccination, might cause them to be more vulnerable to omicron,” Lin commented.

Coronavac is widely used in China and developing countries. Lin expressed his concern that a Coronavac booster shot won’t be as effective against omicron as the vaccines used in the United States, and Sinovac doesn’t have the capability to quickly produce enough booster shots for all its customers around the world.

Epoch Times Photo
People walk past a government banner encouraging the public to take the Covid-19 vaccine in Hong Kong on Aug. 15, 2021. (Bertha Wang/AFP via Getty Images)

The Epoch Times called a government staff member in China who is in charge of vaccinations in one city. He said that a recipient can have a booster shot at least 183 days after the second vaccination.

“You have to take the three shots in turn, and can’t skip the second one to [before getting] the booster,” the government staff said.

The government staff didn’t answer the question about whether the rule is caused by the production capacity limitations of Chinese vaccine manufacturers.

HKU Study

Besides testing the effectiveness of Sinovac’s Coronavac, HKU researchers studied the BNT162b2 vaccines from BioNtech, the German partner of Pfizer. Hong Kong only has two COVID-19 vaccines, Coronavac and BNT162b2.

The results showed that 5 out of the 25 BNT162b2 vaccine recipients had neutralizing ability against the Omicron variant.

The HKU team did not study the vaccination’s effectiveness of the person who had received the booster, but suggested: “A third dose of COVID-19 vaccine is needed to enhance the antibody response against the Omicron variant.”

Clearly, the team suggested that people take BioNtech vaccine because “whether a third dose of the present Coronavac vaccine will enhance the neutralizing antibody response against the Omicron variant remains to be determined,” said the study.

Epoch Times Photo
A trolley carrying Pfizer-BioNTech Comirnaty vaccine is transported to a warehouse after being unloaded from a Cathay Pacific cargo plane at Hong Kong International Airport in Hong Kong, on Feb. 27, 2021. (Jerome Favre – Pool/Getty Images)

The study’s suggestion is in line with a Pfizer-BioNTech statement.

On Dec. 8, Pfizer stated that their initial laboratory study demonstrated that “two doses [of vaccine] show significantly reduced neutralization titers” against the Omicron variant, while “three doses of the Pfizer-BioNTech COVID-19 Vaccine neutralize the Omicron variant.”

Luo Ya contributed to this report. 

Nicole Hao
Nicole Hao is a Washington-based reporter focused on China-related topics. Before joining the Epoch Media Group in July 2009, she worked as a global product manager for a railway business in Paris, France.