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BEIJING / SINGAPORE (Reuters) – Fragmentary releases of efficacy data for the COVID-19 vaccine developed by China’s Sinovac could undermine confidence in the injection, experts warned, as several countries prepare for mass inoculations with the vaccine.
Turkish researchers said Thursday that Sinovac’s CoronaVac was 91.25% effective according to an interim analysis only to see a confusing same-day reading from Brazil that said the vaccine’s efficacy was between 50% and 90%.
Brazil has also delayed the release of its vaccine efficacy data three times as Sinovac seeks to consolidate data from global trials that include Indonesia, Turkey and Chile.
Efficacy data is closely followed, as many developing countries have signed agreements to use the Sinovac vaccine, which is easier to store and transport than rival injections developed by Pfizer and its partners BioNTech and Moderna.
Experts say that it is not unusual for a vaccine to show different efficacy rates in various settings, as testing protocols, data size, and population could affect results, but the way CoronaVac data was published created some confusion.
“You really want the data to be compelling on the first presentation; this is what Pfizer and Moderna accomplished, minus AstraZeneca,” said Jerome Kim, director of the International Vaccine Institute, a Seoul-based non-profit agency dedicated to the vaccine research.
“With multiple ‘leaks’ of data and hints of this or that, you don’t see the same effect with Sinovac; perhaps the final presentation in January will be more compelling.”
Sinovac did not immediately comment.
A spokesman for China’s Foreign Ministry said in a daily briefing on Monday that its vaccine developers were making progress “in strict compliance with scientific principles and regulatory requirements.”
Four other Chinese vaccines from Sinopharm, CanSino Biologics and the Chinese Academy of Sciences are in phase 3 clinical trials.
MORE DATA AND TRANSPARENCY
The Turkish trial data for CoronaVac is based on the analysis of 1,322 participants including 29 infected people, and efficacy evaluations were performed 14 days after the second dose was administered.
Authorities initially planned to announce the results when the number of patients reached 40, but released a mid-term evaluation as the country seeks to grant an emergency use authorization.
Indonesia, which is also considering injection for mass inoculation, confused the world earlier this month when state-owned Bio Farma said the vaccine’s efficacy was 97%. He later clarified that the prevention rate could not yet be determined and that it was necessary to wait for the data to be completed.
“When you can’t release enough details, it’s probably best not to make an announcement like that,” said Paul Griffin, a professor at the University of Queensland who is also conducting several studies on the COVID-19 vaccine.
With efficacy data in Turkey based on only 1,322 subjects and small cases of infection, experts say more data would be needed from a larger number of participants to seek regulatory approval.
“It is difficult to determine how well (the) Sinovac vaccine works based on just 29 cases of coronavirus,” Kim said.
“It would be nice to have more volunteers and more infections, which would increase the strength of the efficacy data.”
That would make data from Brazil crucial, where it has completed a test with 13,000 volunteers, while studies in Turkey and Indonesia involve more than 7,000 and 1,600, respectively.
Some experts cautioned that increased scrutiny was expected in data collection and analysis for COVID-19 vaccines developed in China due to their spotty safety record.
“This needs to be discussed very clearly and transparently. And transparency is one of China’s biggest concerns, especially with its vaccine and also because of its track record,” said Dicky Budiman, an epidemiologist at Griffith University in Queensland.
“So this is one of the most important and crucial moments for China to show the world how they have improved the quality of their vaccines … This is something that they have to explain to the world, of course, through scientific articles.”
(Reporting by Beijing Newsroom, Aradhana Aravindan in Singapore, Stanley Widianto in Jakarta, and Kate Lamb in Sydney; written by Miyoung Kim, edited by Emelia Sithole-Matarise)
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