Photographer: Lintao Zhang / Getty Images
Photographer: Lintao Zhang / Getty Images
A few days before the launch of a global launch, receiving the President of Indonesia Sinovac Biotech Ltd. vaccine on live television, the uncertainty revolves around the effectiveness of the top Chinese shooting, for which four different protection numbers have been released in recent weeks.
Indonesia, which is the fastest to distribute Sinovac photography to its population, said a local study showed a 65% effectiveness against Covid-19. But only 1,620 people in Indonesia took part in the process – too small for significant data.
Turkey said last month that the same vaccine had shown 91.25% efficacy in its local study, which was similarly too small to draw a sufficient conclusion.
In Brazil, where the largest Sinovac trial with more than 13,000 people takes place, the effectiveness rates of the duels have been published. The company’s local process 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.
However, a local news site reported this week that the “true” effectiveness rate was between 50% -60%, citing unnamed sources. The Butantan Institute said it was “speculative” and would publish additional data on Tuesday.
Overlapping efficacy data are unprecedented in the Covid-19 vaccine race – AstraZeneca Plc launched two separate protection rates last month based on different dosing regimes – and all findings are above the 50% effectiveness threshold required by regulators for approval.
China is fighting to make the world trust its vaccines
However, the confusion that arises when several governments commit to inoculating their citizens with Sinovac’s shooting is fueled by skepticism about Chinese vaccines, which revealed less safety and testing information than the first in the West. Combating the data risks further undermining confidence in the photos that President Xi Jinping promised to share with the rest of the world as a global public good.
“There is enormous financial and prestige pressure for these studies to massively overestimate their 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 properly control the pandemic now want to exaggerate the benefits of vaccines to win votes and alleviate local unrest.”
A Sinovac spokesman declined to comment on figures from his trials in Brazil, Turkey and Indonesia and said more data would be released by his Brazilian partner this week.
The data issue already seems to support regulatory approval for the Sinovac vaccine in some places.
“Initially, Sinovac was to deliver the vaccine to Hong Kong in January. But they have three times delayed the announcement of the phase III clinical trial data, “said David Hui, a professor of respiratory medicine at the Chinese University of Hong Kong, who is on the advisory board of the Asian financial center Covid-19. “That would delay the evaluation of their application.”
Computational confusion
The massive trial in Brazil, which Sinovac said will be the place to get its final efficacy data, has received intense scrutiny.
Observers were shaken by the first 78% effectiveness rate announced by the Butantan Institute. According to the information revealed, the study saw approximately 220 infected participants: 160 in the placebo group and almost 60 in the vaccinated group.
If study participants were divided equally between the vaccine and the placebo group, then the efficacy rate should reach 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 group and the vaccinated group, are published in peer-reviewed scientific journals, said Raina MacIntyre, head of the biosecurity program at Kirby Institute. from the University of New South Wales.
It remains unclear whether the Sinovac trial in Brazil deviated to some extent from its protocol. This was the case with the photography developed by AstraZeneca and Oxford University: a 90% protection rate was found when half a dose was first administered, followed by a full dose, which was made by mistake. Two complete doses, as designed by the researchers, showed an efficacy of only 62%.
Brazilian regulator Anvisa is requesting additional data from the Butantan Institute on the Sinovac shot study, including whether the dose deviation and its impact occurred, before deciding whether to approve the vaccine for use.