With trials of Sinovac Biotech Ltd.’s coronavirus vaccine. in Brazil and Turkey, suggesting that the injection has a 90% protection rate on both sides, there is still no definitive assessment of how effective it is in protecting people from Covid-19.
Sinovac is completing the results of Phase III studies conducted in Brazil, Turkey, Indonesia and Chile, according to a person familiar with the studies. Those tests are relatively independent of each other and are conducted according to different protocols, rather than subject to uniform standards typical of such studies, 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 full information about Sinovac’s vaccine, only saying it was found to be more than 50% effective. Sao Paulo State Secretary of Health Jean Gorinchteyn offered more specific guidelines on Thursday, saying the vaccine “ did not achieve 90% efficacy, ” which would make it less successful than those developed by Pfizer Inc. and From Moderna Inc.
“We don’t know how much more than 50% it was, whether it was 60%, 70% or 80%, but it’s at a level that allows us to reduce the impact of the disease on our population,” Gorinchteyn said an interview with Brazilian CBN Radio. “We knew the effectiveness would never reach 90%.”
Turkey Trial
Add to the confusion, Turkey said a trial of Sinovac’s vaccine taking place in his country showed an estimated efficacy of 91.25%. However, that trial is based on only 29 cases, which, according to the person familiar with the trials, is considered insufficient to draw a definitive conclusion about the effectiveness of the shot. The trial will continue to collect Covid-19 cases to get a more definitive reading, the person said.
A Sinovac spokesman declined to comment on questions about the vaccine’s efficacy.
The delay in announcing the final results has created confusion about the effectiveness of Sinovac’s shot. Chinese developers have been slow compared to their Western peers in releasing efficacy data, threatening to erode confidence in these candidates as the world imposes a laser focus on which vaccines are most successful in the fight against the pandemic.
Meanwhile, Pfizer and Moderna shots have been shown to reduce symptomatic cases by more than 90%.
China’s race ahead Covid-19 Vaccine raises safety questions
The reason Brazil hasn’t released full efficacy figures yet is because Sinovac and its partners are reviewing all Covid-19 cases found among participants, the person said. The Brazilian trial has yielded more than 170 cases, but Sinovac must verify them to see if they all meet the criteria set by the Chinese drug regulator.
According to the person, regulators from China and Brazil, as well as Sinovac and his partners, are still analyzing data from the Brazilian trial. Ultimately, Sinovac hopes to see uniform standards to ensure equal comparisons between different trial sites, the person said. According to the protocol for the trial in Brazil, Covid-19 cases are diagnosed in accordance with the guidelines of the United States Food and Drug Administration.
The late-stage study of Sinovac’s vaccine in Brazil, involving approximately 13,000 participants suggested the shot is “safe and effective,” authorities from the Butantan Institute and Sao Paulo state said earlier this week.
Saving lives
Sinovac is betting on a successful vaccine to inoculate more people around the world and save lives, especially in developing countries like Brazil that have limited access to the Pfizer and Moderna shots. Sinovac’s shot may be better suited for developing countries because it can be kept at normal refrigerator temperatures, while Pfizer and Moderna vaccines require frozen conditions for storage and transportation.
The Sinovac vaccine has been at the center of a political dispute between Sao Paulo Governor Joao Doria and President Jair Bolsonaro, who says a vaccine from China cannot be trusted. Bolsonaro again cast doubts about the effectiveness of the Sinovac vaccine in a Christmas Eve speech broadcast on Facebook.
“I want to make it very clear that the label of this vaccine will be ‘we are not responsible for any side effects’. The responsibility is yours, ”he said.
– With help from Andrew Rosati and Dong Lyu