With tests of The coronavirus vaccine from Sinovac Biotech Ltd. in Brazil and Turkey, suggesting that the injection has a protection rate on both sides of 90%, there is still no final assessment of its exact effectiveness in protecting people against Covid-19.
Sinovac is finalizing the results of the phase III tests carried out in Brazil, Turkey, Indonesia and Chile, according to a person familiar with the tests. These tests are relatively independent of each other and conducted according to different protocols, rather than being subject to the unified standards that normally govern these tests, said the person, who asked not to be identified because the data is not public.
Researchers in Brazil earlier this week delayed the release of complete information about the Sinovac vaccine, saying only that it was found to be more than 50% effective. The Secretary of Health of the State of São Paulo, Jean Gorinchteyn, offered more specific guidelines this Thursday, saying that the vaccine “did not reach 90%” of effectiveness, which would make it less successful than those developed by Pfizer Inc. and Moderna Inc.
“We don’t know how much more than 50%, if it was 60%, 70% or 80%, but it is at levels that allow us to reduce the impact of the disease on our population,” said Gorinchteyn in an interview with Rádio CBN do Brasil. “We knew that the effectiveness would never reach 90%.”
To add to the confusion, Turkey said a trial with the Sinovac vaccine taking place in his country showed an estimated effectiveness rate of 91.25%. This judgment, however, is based on only 29 cases, which is considered insufficient to draw a definitive conclusion about the effectiveness of the shot, according to those familiar with the trials. The trial will continue to collect Covid-19 cases for further reading, the person said.
A Sinovac spokesman declined to comment on questions about the vaccine’s effectiveness.
The delay in announcing the final results created confusion about the effectiveness of Sinovac’s shot. Chinese developers have been slow compared to their Western peers in releasing efficacy data, risking an erosion of confidence in these candidates as the world puts a laser focus on which vaccines are most effective in combating the pandemic.
Pfizer and Moderna injections, in turn, have been shown to reduce symptomatic cases by well over 90%.
Race from China to Covid19 Vaccine raises safety issues
The reason Brazil has not yet released the full effectiveness figures is because Sinovac and its partners are reviewing all Covid-19 cases found among participants, the person said. The Brazilian trial yielded more than 170 cases, but Sinovac needs to check them to see if they all meet the criteria set by the Chinese drug regulator.
Regulators from China and Brazil, in addition to Sinovac and its partners, are still in the process of analyzing the trial data in Brazil, according to the person. Ultimately, Sinovac hopes to see unified standards to ensure equal comparisons at different test sites, the person said. The protocol for testing in Brazil says that Covid-19 cases are diagnosed according to the guidelines of the US Food and Drug Administration.
The advanced-stage trial of the Sinovac vaccine in Brazil, involving about 13,000 participants suggested that the injection is “safe and effective,” officials at the Butantan Institute and the state of São Paulo said earlier this week.
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. Sinovac injection is potentially more suitable for developing countries because it can be kept at normal refrigerator temperatures, while Pfizer and Moderna vaccines require deep freezing conditions for storage and transport.
The Sinovac vaccine has been at the center of a political dispute between São Paulo governor João Doria and President Jair Bolsonaro, who says that a vaccine from China is unreliable. Bolsonaro again cast doubt on the effectiveness of the Sinovac vaccine in a Christmas Eve speech broadcast on Facebook.
“I want to make it very clear that the label for this vaccine will be ‘we are not responsible for any side effects’. The responsibility is yours, ”he said.
– With the help of Andrew Rosati and Dong Lyu