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BRASILIA (BLOOMBERG) – A Covid-19 vaccine developed by Chinese pharmaceutical firm Sinovac Biotech Ltd was found to be more than 50 percent effective in a Brazilian clinical trial, although researchers delayed releasing more information at the company’s request.
A 50 percent efficacy rate is the minimum standard set by US regulators for the emergency authorization of Covid vaccines.
The Messenger RNA vaccines from Moderna Inc and Pfizer Inc have produced much better results, reducing cases of symptomatic Covid by more than 90% in giant trials.
Chinese vaccine developers have been slow compared to their Western peers in publishing efficacy data for their vaccines.
With millions of healthy people counting on transparency in trials prior to receiving an injection, the lack of more specific results from the Sinovac trial runs the risk of eroding trust in China’s vaccines.
Hong Kong said on Wednesday (December 23) that residents will be able to choose which shot they want to take from among various candidates likely to include Sinovac.
The lack of transparency in the report of the Brazil trial results “is totally unacceptable” and would not be reviewed in the United States, Dr. Eric Topol, a clinical trial expert and director of the Scripps Research Translational Institute, said in a telephone interview.
“This doesn’t look good at all.”
Sinovac did not respond to calls outside of office hours.
A spokesperson said earlier this week that the company could only release efficacy data after it is reviewed by Chinese regulators.
‘CAUSE OF CELEBRATION’
The late-stage trial of the Sinovac vaccine in Brazil, involving some 13,000 participants, suggested the injection is “safe and effective,” officials from the Butantan Institute and the state of Sao Paulo said.
They were asked not to release the information until it was thoroughly reviewed in China as part of a contractual agreement, they said.
“Our goal was for the injection to be more than 50 percent effective,” State Health Secretary Jean Gorinchteyn told a news conference.
“A vaccine that reaches at least that is already cause for celebration.”
The group that received the vaccine in the Brazil trial had no severe cases of Covid-19 and the main reported side effect was mild pain at the injection site, said Professor Dimas Covas, director of Butantan.
Efficacy is above the threshold necessary for a vaccine to be registered by Brazil’s health regulator Anvisa, which has yet to approve the injection, he said.
The trial produced efficacy data that differed from tests conducted in other countries, Dr. Gorinchteyn said, without elaborating.
He added that Sinovac’s review of the data is scheduled to take 15 days, but could take less than that, and should not delay the start of scheduled Jan.25 inoculations with the Sinovac vaccine.
DATA CONSISTENCY
“Sinovac has several ongoing trials and it is important that it provides consistency to the data,” said Professor Covas.
“The company cannot analyze data for the same vaccine using different criteria and it cannot have three different efficacy rates for the same vaccine.”
China’s request to delay the efficacy announcement and share the data came at around 9 p.m. local time on Tuesday, the researchers said.
Sinovac is also conducting tests in Indonesia and Turkey.
It is routine for trials of a drug or vaccine conducted in different patient groups or locations to produce slightly different results, and research groups generally report the results of independent trials separately.
However, while Butantan and state authorities reiterated their optimism about the injection, Dr. Topol said that the fact that Brazilian authorities only say the vaccine is more than 50 percent effective, but do not provide further details, suggests that Sinovac’s efficacy results may not be as good as those achieved by Pfizer and Moderna Inc.
SAVING LIVES
Sinovac is betting on a successful vaccine to inoculate more people around the world and save lives, especially in developing countries like Brazil, which will have limited access to Pfizer and Moderna vaccines.
Vaccines from Sinovac and other Chinese companies could also help their home country gain geopolitical influence and restore an image tarnished by criticism of its initial response to the virus.
Sinovac injection is potentially more suitable for developing countries because it can be kept at normal refrigerator temperatures.
In contrast, Pfizer and Moderna mRNA vaccines require deep-frozen conditions for storage and transportation, complicating distribution.
The data delay is also a major blow to Sao Paulo Governor Joao Doria’s plan to gain swift approval and begin vaccinating the state of some 45 million people in January.
It is trying to act quickly while the central government lags on supply agreements and specific vaccination dates.
Millions of doses of Sinovac’s vaccine, called CoronaVac, have already been shipped to Sao Paulo.
The Sinovac vaccine has been at the center of a political dispute between Doria and President Jair Bolsonaro, who says a vaccine from China cannot be trusted.
Bolsonaro, who does not plan to receive any coronavirus vaccines after being infected earlier this year, has openly discussed with Doria, considered a candidate for the 2022 presidential elections.
In addition to the central government of Brazil, Butantan is in talks to sell the vaccine to Argentina, Uruguay, Peru, Ecuador and Honduras.
Chile is in talks directly with the Chinese company, according to Professor Covas.
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