Photographer: Lintao Zhang / Getty Images
Photographer: Lintao Zhang / Getty Images
Days before a global launch begins, with the President of Indonesia receiving the Sinovac Biotech Ltd. vaccine on live television, uncertainty revolves around the effectiveness of the main Chinese injection, for which four different numbers of protection rates have been released in recent weeks.
Indonesia, which is moving faster in distributing the dose of Sinovac to its population, said a local trial showed 65% effectiveness against Covid-19. But only 1,620 people in Indonesia participated in that test – too small for significant data.
Peru said last month that the same vaccine showed 91.25% efficacy in its local test, which was too small to draw enough conclusions.
In Brazil, where the largest Sinovac trial with more than 13,000 people is being conducted, duel efficacy rates have been released. The company’s local testing partner, Instituto Butantan, 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 site reported this week that the “real” rate of effectiveness was between 50% -60%, citing unidentified sources. The Butantan Institute said this was “speculative” and would release additional data on Tuesday.
The overlapping of efficacy data is not unprecedented in the Covid-19 vaccine race – AstraZeneca Plc launched two separate protection fees based on different dosing regimens last month – and all findings are above the 50% effectiveness limit required by regulators for approval.
China is struggling to make the world trust its vaccines
However, the confusion that arises when several governments pledge to inoculate their citizens with the Sinovac injection is fueling skepticism about Chinese vaccines, which revealed less safety and testing information than Western competitors. The confusion of data risks further undermining confidence in the shots that President Xi Jinping has promised to share with the rest of the world as a global public good.
“There is enormous financial and prestigious pressure for these tests to massively exaggerate their results,” said Nikolai Petrovsky, a professor at the Faculty of Medicine and Public Health at Flinders University.
“In many cases, these exaggerations are also politically motivated, as countries that have failed to control the pandemic properly now want to overstate the benefits of vaccines to win votes and appease local unrest.”
A Sinovac spokesman declined to comment on his test numbers in Brazil, Turkey and Indonesia and said that more data will be released by his partner in Brazil this week.
The data issue seems to be already delaying regulatory approval for the Sinovac vaccine in some places.
“Initially, Sinovac would dispatch the vaccine supply to Hong Kong in January. But they delayed the announcement of Phase III clinical trial data three times, ”said David Hui, a professor of respiratory medicine at the Chinese University of Hong Kong who is part of the Covid-19 advisory panel at the Asian financial center. “This would delay the evaluation of your application.”
Calculation confusion
Brazil’s huge trial, which Sinovac said will be where he will get his definitive efficacy data, received intense scrutiny.
Observers were perplexed by the first 78% effectiveness rate announced by the Butantan Institute. According to the information released, the study saw about 220 infected participants: 160 in the placebo group and almost 60 in the vaccinated group.
If trial participants are divided equally between the vaccine and placebo group, then the efficacy rate should reach 62.5%, said Petrovsky, who is also director of research at Vaxine Pty Ltd., a company that is developing a Covid-19 vaccine.
External calculations remain speculative unless more data, such as the total number of people in the placebo group and the vaccinated group, are released in peer-reviewed scientific journals, said Raina MacIntyre, head of the University of New York’s Kirby Institute Biosafety Program. South Wales.
It is not yet clear whether the Sinovac test in Brazil has deviated to some extent from its protocol. This is what happened with the injection developed by AstraZeneca and the University of Oxford: a protection rate of 90% was found when a half dose was applied first, followed by a full dose, which was done by mistake. Two full doses designed by the researchers showed an effectiveness of only 62%.
Brazil’s drug regulatory agency, Anvisa, is requesting additional data from the Butantan Institute on the Sinovac vaccine trial, including whether deviation in dosage and its impact, before deciding whether to approve the use of the vaccine.