Photographer: Lintao Zhang / Getty Images
Photographer: Lintao Zhang / Getty Images
Days before a world launch begins and the president of Indonesia receives the The Sinovac Biotech Ltd. vaccine on live television it makes uncertainty revolve around the effectiveness of the leading Chinese feature, for which four different protection figures have been released in recent weeks.
Indonesia, which moves faster in distributing the Sinovac trait to its population, said a local trial showed a 65% effectiveness against Covid-19. But only 1,620 people in Indonesia participated in this trial, too small to get meaningful data.
Turkey said last month that the vaccine itself showed a 91.25% efficacy in its local trial, which was too small to draw a sufficient conclusion.
In Brazil, where the largest trial of Sinovac with more than 13,000 people is taking place, the effectiveness rates of the duel have been publicized. The company’s local testing partner, the 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” effectiveness rate was between 50% and 60%, citing unnamed sources. The Butantan Institute said this was “speculative” and would release additional data on Tuesday.
Overlapping efficacy data are not unprecedented in the Covid-19 vaccine race – AstraZeneca Plc published two different protection indices based on different dosing regimes last month, and all findings are above the 50% efficacy threshold required by regulators for approval.
China is struggling to get the world to trust its vaccines
However, the confusion, which occurs when several governments commit to inoculating their citizens with the shooting of Sinovac, is feeding skepticism about Chinese vaccines, which have revealed less safety and testing information than front-westerns. The data problem runs the risk of further undermining confidence in the traits that President Xi Jinping has promised to share with the rest of the world as a global public good.
“There is enormous financial and prestige pressure for these trials to massively exaggerate their results,” said Nikolai Petrovsky, a professor at the College of Medicine and Public Health at Flinders University.
“In many cases, these exaggerated statements also have political motivation, as countries that have not been able to properly control the pandemic now want to exaggerate the benefits of vaccines to win votes and appease local unrest.”
A Sinovac spokesman declined to comment on the numbers of his trials in Brazil, Turkey and Indonesia and said he would post more data this week for his Brazilian partner.
It appears that the data problem already holds the regulatory approval of the Sinovac vaccine in some places.
“Initially, Sinovac was going to send the supply of vaccines 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 Asian financial center’s advisory panel.” would delay the evaluation of your application “.
Calculus confusion
The massive trial in Brazil, which Sinovac has said will be where it will get its final efficacy data, has received intense scrutiny.
Observers were baffled by the first 78% effectiveness rate announced by the Butantan Institute. According to the information released, the trial infected about 220 participants: 160 in the placebo group and almost 60 in the vaccinated group.
If trial participants were evenly distributed between the vaccine group and the placebo group, the efficacy rate should reach 62.5%, said Petrovsky, who is also research director of Vaxine Pty Ltd ., a company that develops 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 University’s Kirby Institute Biosecurity Program. of New South Wales.
It is still unclear whether Sinovac’s trial in Brazil deviated to some extent from its 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 in error. Two full doses designed by the researchers showed an efficacy of only 62%.
Brazilian drug regulator Anvisa is requesting additional data from the Butantan Institute on the Sinovac trial, which includes whether a dose deviation and its impact occurred, before deciding whether to approve the vaccine. for use.