Photographer: Lintao Zhang / Getty Images
Photographer: Lintao Zhang / Getty Images
Days before a global rollout begins and the President of Indonesia does it Sinovac Biotech Ltd. vaccine on live television, is stirring uncertainty about the efficacy of the leading Chinese shot, for which four different protection rates have been released in recent weeks.
Indonesia, which is moving fastest in spreading the Sinovac shot among its population, said a local trial showed 65% efficacy against Covid-19. But only 1,620 people in Indonesia took part in that trial – too small for meaningful data.
Turkey said last month that the same vaccine showed 91.25% efficacy in its local trial, which was also too small to draw a conclusive conclusion.
In Brazil, where Sinovac’s largest trial of more than 13,000 people is being conducted, dueling efficacy rates have been reported. The company’s local pilot partner, Butantan Institute, said last week that the vaccine was 78% effective in preventing mild cases of Covid-19 and 100% effective against severe and moderate infections.
Still a local news website reported this week that the “true” efficacy rate was between 50% -60%, citing unnamed sources. Butantan Institute said this was “speculative” and would release additional data Tuesday.
Overlapping efficacy data is not unknown in the Covid-19 vaccine race – AstraZeneca Plc released two separate percentages of protection based on different dosing regimens last month – and all findings are above the 50% efficacy threshold required by regulators for approval.
China is struggling to make the world rely on its vaccines
But the confusion that arises when different governments commit to inoculating their citizens with Sinovac’s shot is fueling skepticism about Chinese vaccines, which have revealed less safety and testing information than Western frontrunners. The data outage threatens to further undermine confidence in recordings that President Xi Jinping has promised to share with the rest of the world as a global public good.
“There is tremendous financial and prestige pressure for these studies to massively exaggerate the results,” said Nikolai Petrovsky, a professor at the College of Medicine and Public Health at Flinders University.
“In many cases, such exaggerations are also politically motivated, as countries that have failed to get the pandemic under control now want to exaggerate the benefits of the vaccines to win votes and soothe local unrest.”
A Sinovac spokesman declined to comment on the numbers of his investigations in Brazil, Turkey and Indonesia, saying more data would be released this week by his Brazilian partner.
The data issue already appears to be hampering regulatory approvals for Sinovac’s vaccine in some places.
Initially, Sinovac would ship the vaccine stock to Hong Kong in January. But they have three times delayed the release of the Phase III clinical trial data, ”said David Hui, a professor of respiratory medicine at the Chinese University of Hong Kong, who sits on the Asian Financial Hub’s Covid-19 advisory panel. . “That would delay the evaluation of their application.”
Confusion in the calculation
The massive study in Brazil, which Sinovac has said will get its final efficacy data, has been intensively investigated.
Observers were confused by the first 78% efficacy rate announced by Butantan Institute. According to the information disclosed, approximately 220 participants were infected in the study: 160 in the placebo group and nearly 60 in the vaccinated group.
If subjects were evenly divided between the vaccine and placebo groups, the efficacy would be 62.5%, said Petrovsky, who is also the research director for Vaxine Pty Ltd., a company developing a Covid-19 vaccine.
External calculations remain speculative unless more data, such as the total number of people in the placebo and vaccinated groups, is released in peer-reviewed scientific journals, said Raina MacIntyre, head of the Biosecurity Program at the Kirby Institute at the University of New South. Wales.
It remains unclear whether the Sinovac trial in Brazil deviates somewhat from the protocol. This was the case with the shot developed by AstraZeneca and Oxford University: a protection rate of 90% was found when a half dose was first administered, followed by a full dose, which was done accidentally. Two full doses, as designed by researchers, showed only 62% efficacy.
Brazilian drug regulator Anvisa is requesting additional data from the Butantan Institute on the Sinovac shot trial, including whether there has been a dose deviation and its impact, before deciding whether to approve the vaccine for use.