Analysts said the effectiveness of Sinovac’s Coronavac vaccine in Brazil – the lowest among its global competitors – could affect international confidence in Chinese-made vaccines and hamper Beijing’s efforts to repair its image from its early mismanagement of the original outbreak by supplying Covid-19 vaccines to developing countries.
The Butantan Institute and the Government of Sao Paulo report that the coronavirus vaccine achieved an overall efficacy rate of 50.38% in the clinical trial conducted in Brazil, in addition to (an efficacy rate of 78% for mild cases and 100% for moderate and severe cases of “All rates are higher than the 50% level required by the WHO (World Health Organization),”
The razor-sharp margin for regulatory approval is likely to lead to concern among researchers as the Butantan Institute last week released partial “clinical efficacy” results that celebrated 78% to 100% efficacy in preventing infections.
The state body funded Phase 3 trials of the vaccine, which involved 13,000 health workers in eight Brazilian states.
“In terms of the overall effectiveness of the analysis, we met the requirements of the World Health Organization by 50.38%,” Ricardo Palacios, medical director of clinical research at the Butantan Biomedical Center in Sao Paulo, said Tuesday during a news conference.
But on Tuesday, senior members of the Brazilian Ministry of Health told CNN-affiliated CNN Brasil that “efficiency is cross-border,” and that because “It’s at the border. We have to wait for ANVISA (Brazilian Health Regulatory Agency) to assess.”
A representative of Sinovac said the company is discussing the outcome but refuses to comment further. The final efficacy of the vaccine will be determined by China’s drug regulator, the National Medical Production Administration, according to the representative.
Potential stumbling blocks
Yanzhong Huang, a senior global health fellow at the U.S.-based Foreign Relations Council, described his impact on 50.38% of the Sinovac vaccine as a “disappointing” result that had surprised him.
The results suggest that Coronavac is less effective than alternative vaccines developed by Pfizer-BioNTech and Moderna, which have an efficacy rate of approx. 95%.
Russia says its Sputnik V vaccine is 91% effective, while the British vaccine, developed by Oxford University and AstraZeneca, has an average efficacy of 70%.
Despite the worse-than-expected results, Huang said the Sinovac vaccine would still be “useful” in helping relieve pressure on health systems while reducing potential deaths given its higher efficacy in moderate and severe cases that would require medical treatment.
However, the low overall efficiency may hinder Sinovac’s ability to expand its market share globally, Huang said.
Sinovac has signed agreements to supply 46 million doses of its Covid-19 vaccine to Brazil, 50 million doses to Turkey and 7.5 million doses to Hong Kong. It also supplies 40 million doses of vaccine mass – the vaccine concentrate before it is divided into vials – to Indonesia for local production.
“As many countries are planning to order or have already ordered Sinovac vaccines, it may undermine people’s willingness to take them because people may question the usefulness of the vaccines,” Huang said. “It could be a potential stumbling block.”
Lack of transparency
Both Sinovac and Sinopharm have had questions about data release. When state-owned Sinopharm announced its efficacy results, it did not provide details on its clinical trial data. A Sinopharm director said detailed data will be released later and published in scientific journals without providing a timeline.
There is also the issue of inconsistency in results from clinical trials conducted at different sites.
After virtually eliminating coronavirus within its borders earlier last year, Chinese drug manufacturers had to search abroad for sites to test the effectiveness of their vaccines. But the results reported so far are far from consistent.
Sinopharm’s efficacy rate of 79%, for example, is lower than the 86% announced by the United Arab Emirates for the same vaccine in December.
Last week, Brazil’s health regulatory agency ANVISA Butantan Institute said that in order to approve the use of a vaccine in emergencies, the global efficacy rate had to be made public – information the institute had not received from Sinovac at the time, according to CNN Brasil sources.
ANVISA will meet on Sunday to decide on two requests for emergency use of both the Coronavac vaccine and the Oxford University AstraZeneca vaccine.
The news could potentially also hinder China’s own coronavirus vaccination drive, Huang warned.
China has vaccinated tens of thousands of people with Sinovac’s vaccine since July under a government-approved emergency use program that includes at least three Chinese vaccine candidates.
Chinese public health experts have repeatedly told the public that they are convinced that Chinese-made vaccines are at least as good as, if not better, than foreign alternatives, Huang said.
“If people learn about this, they may begin to question the safety and efficacy of the Sinovac vaccine or even other Chinese-made vaccines,” Huang said. “I think the government will have to do some convincing work on either those who have already taken the shots or are about to do so.”