Findings from Turkey and Brazil Tremble the Trust in Sinovac’s CoronaVac

Chunks of releases on efficacy data for the COVID-19 vaccine developed by China’s Sinovac could shake the confidence in the shot, according to experts. They are warning regarding the efficacy of the shot as many countries are getting ready for mass immunization with the vaccine.

Conflicting Efficacy Rates

On Thursday, Turkish researchers stated that Sinovac’s CoronaVac was 91.25% effective depending on an interim analysis.  However, the preliminary results were based on a small clinical trial and none of the data was posted online or published in a journal. The news got confusing when on the same day Brazil released a statement which said the vaccine’s efficacy was between 50% and 90%.

Brazil has also halted release of its efficacy data on the vaccine almost three times, as Sinovac is waiting for consolidating the data from global trials that consist of Turkey, Indonesia, and Chile.

The data on efficacy is closely being observed as many developing countries have undergone deals to utilize the Sinovac vaccine which considered being easily storable and transportable as compared to its rival vaccines developed by Pfizer and its partner BioNTech and Moderna.

Experts are saying that it’s not rare for a vaccine to exhibit different efficacy rates depending on various settings. The data can vary according to trial protocols, data size, and population. However, the way CoronaVac data has been rolled out led to a stream of confusion.

A total of 7,371 volunteers were included in the Turkish trial; however, the efficacy data provided by Serhat Unal, an infectious diseases expert, was based only on 1,322 participants, 752 of whom received a real vaccine and 570 of whom got the placebo.

Improving Transparency in Data

“You really want the data to be compelling at first presentation; this is what Pfizer and Moderna achieved, AstraZeneca less so,” according to Jerome Kim who is the head of the International Vaccine Institute, which is a non-profit agency based in Seoul dedicated to research in vaccine.

“With multiple ‘leaks’ of data and suggestions of this or that you don’t see the same effect with Sinovac; perhaps the final presentation in January will be more compelling.”

Sinovac didn’t provide a prompt comment. On Monday, a Chinese foreign ministry spokesman said during a daily briefing that its vaccine developers were moving forward “in strict adherence to scientific principles and regulatory requirement.”

Four other vaccine candidates from China from Sinopharm, CanSino Biologics, and the Chinese Academy of Sciences are currently in Phase 3 of their clinical trials.

As explained above the Turkish trial data for CoronaVac is based on analysis of 1,322 participants which consisted of 29 infected people, and efficacy evaluations were calculated 14 days after the second dose was injected.

Initially, authorities had planned to declare the results when the number of patients reached 40; however, released interim evaluation as the country was looking to issue an emergency use authorization.

Wait for Consolidated Data is Necessary

Indonesia, which is also considering the vaccine for mass immunization, puzzled the world earlier this month when state-owned Bio Farma stated that the efficacy of the vaccine was 97%. It later made it clear that the prevention rate could not be determined yet and it was important to wait for the consolidated data.

“When you are not able to release sufficient details, it’s probably better not to make your announcement like that,” according to Paul Griffin who is a professor at the University of Queensland and is also executing a number of COVID-19 vaccine studies.

Considering the efficacy data in Turkey based on a small group of subjects and few infection cases, experts explain that more data from a bigger number of participants would be required to get regulatory approval.

“It’s difficult to determine how well (the) Sinovac vaccine works based solely on 29 coronavirus cases,” Kim said.

“It would be good to have more volunteers and more infections, which would boost the robustness of the efficacy data.”




China’s Patchy Safety Track Record

Due to this, the data from Brazil is crucial as the country has completed a trial with 13,000 volunteers, while studies in Turkey and Indonesia involve over 7,000 and 1,600 respectively.

Some experts issued warnings of greater was expected on data compilation and analysis on the vaccines for COVID-19 developed in China because of its patchy safety track record.

“This should be analyzed very clearly and transparently. And transparency is one of the biggest concerns for China, especially with their vaccine and also because of their track record,” said Dicky Budiman, an epidemiologist at Queensland’s Griffith University.

“So this is one of the very important and crucial times for China to show the world how they have improved the quality of their vaccines. This is something they have to explain to the world, through of course scientific papers.”

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