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New Trial Results Show Chinese Vaccine only 50 Percent Effective

A refrigerated container with 'CoronaVac' COVID-19 vaccines, developed by Sinovac Biotech, arrives at Viracopos International Airport, in Campinas, Brazil December 24, 2020. (REUTERS/Amanda Perobelli)
New Trial Results Show Chinese Vaccine only 50 Percent Effective
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A new Brazilian trial of one of China’s COVID-19 vaccines found that the treatment was only effective about 50 percent of the time.

The CoronaVac vaccine was developed by China’s Sinovac Biotech company. On Tuesday, researchers said a new late-stage trial in Brazil showed the vaccine was just 50.4 percent effective at preventing symptomatic infections. The Brazilian trial included data on what the researchers called “very mild” COVID-19 cases.

Last week, researchers said the vaccine had performed with 78 percent effectiveness against “mild to severe” cases. CoronaVac is one of several vaccines being developed by Chinese companies.

On New Year’s Eve, China approved its first COVID-19 vaccine for use by the public in China. The developer of that vaccine, Sinopharm, said early test data showed that its shots were 79 percent effective. However, the company did not release detailed information about the studies and said research and trials were still going on.

Several nations have completed agreements with Sinovac Biotech to receive the CoronaVac vaccine. Both Malaysia and Singapore have such agreements. The latest results from the Brazilian trial led those countries to say that they will seek more data on the vaccine’s effectiveness before approving and buying supplies.

The chairman of Sinovac Biotech, Yin Weidong, defended the performance and safety of the vaccine after the new results were released. He told reporters the Brazilian trial results “are sufficient to prove that CoronaVac’s safety and effectiveness are good around the world.”

The Sinovac Biotech chief added that, while different countries used vaccines from the same batch in their trials, they did not use the same testing methods.

Health experts have raised concerns about the testing and trials of CoronaVac and other Chinese vaccines. They say the Chinese vaccines have not gone through the same public scrutiny as vaccines developed in the United States and Europe. The experts have called for more data on the trials to be shared.

The new data from Brazil was released just as Indonesia began its vaccination campaign. Reports say that President Joko Widodo was first in the country to receive the CoronaVac vaccine.

Malaysia said Wednesday it would only move forward with plans to receive the vaccine if the shots met all local requirements for safety and effectiveness. The Malaysian company Pharmaniaga Bhd signed a deal Tuesday with Sinovac to buy 14 million doses of CoronaVac and later to manufacture the vaccine locally.

Singapore said it will wait and examine official data released by Sinovac before deciding whether to approve the vaccine.

Thailand, which has ordered 2 million doses of CoronaVac, said it was still planning on receiving the vaccine starting next month. But it added that officials will also seek more trial data directly from Sinovac.

I’m Bryan Lynn.

Reuters reported on this story. Bryan Lynn adapted the report for Learning English. Mario Ritter, Jr. was the editor.

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Words in This Story

late-stage –adj. in the final steps of developing something like a product that requires a lot of testing

symptomatic – adj. showing signs of disease

mild – adj. not severe

sufficient – adj. enough, providing as much as is needed

batch – n. an amount of something that is made at one time

scrutiny – n. careful examination in a critical way

dose – n. the amount of something, such as a medicine, that is needed to have the expected result