By Samantha Pearson and Luciana Magalhaes in São Paulo and Chao Deng in Tapei 

China's Sinovac vaccine has shown to be 78% effective against Covid-19 in Brazilian late-stage trials and offers total protection against severe cases of the disease, raising hopes it can be used to immunize much of the developing world.

Brazil's Butantan Institute, the São Paulo-based research center that tested CoronaVac in Phase 3 trials, said Thursday that none of the volunteers who took the vaccine developed severe cases of Covid-19. More than 12,000 health workers took part in Phase 3 trials in Brazil, the first country to complete tests of Sinovac's vaccine.

"It's a great result," said Luiz Carlos Dias, part of a Covid-19 task force of researchers at the University of Campinas in São Paulo state. "If it can prevent severe cases, hospitalizations, deaths, it will help get us out of this pandemic."

CoronaVac's vaccine is less effective then those being developed by Moderna Inc. and jointly by Pfizer Inc. and BioNTech SE that have shown to have efficacy rates of 94.5% and 95% in testing, respectively. But CoronaVac can be kept in a standard refrigerator between about 36 and 46 degrees Fahrenheit, making it easier and cheaper to transport and store in less developed countries, infectious disease specialists said.

Prashant Yadav, a global health specialist at Washington-based think tank Center for Global Development, said 78% is a high enough rate for many developing countries to consider using the vaccine and potentially good enough for the World Health Organization to consider incorporating CoronaVac into its global distribution system.

"There are a large number of developing countries that haven't been able to secure supplies," he said. "This could become a very viable option for them."

Butantan said it is now requesting authorization for emergency use of the vaccine in Brazil. It is also in talks to start shipping CoronaVac to Argentina, Bolivia, Colombia, Honduras, Peru and Uruguay as of May.

Sinovac's vaccine was approved for emergency use by Beijing in July, along with two other vaccine candidates by Chinese state-owned vaccine maker Sinopharm. So far, Beijing has only approved one of Sinopharm's vaccines for broader use in the country. The green light came after Sinopharm reported its vaccine to be 79% effective, based on interim analysis.

Unlike the vaccines developed by Modern and Pfizer that use new types of genetic-codes, CoronaVac uses weakened forms of the virus to induce an immune response -- a more traditional method that tends to produce lower efficacy rates, researchers said.

With Covid-19 largely under control in China, the country's vaccine developers have had to go abroad to conduct their clinical trials.

Researchers in Turkey, which is at an earlier stage of testing CoronaVac, said in late December that initial data from around 1,300 people in late-stage trials showed the vaccine to be just over 91% effective. Indonesia has also been testing the vaccine but Phase 3 results aren't yet available.

Butantan's director, Dimas Covas, didn't comment on the possible reason for Turkey's higher result, saying that he expected Sinovac to consolidate the results from the three countries into one single efficacy rate.

In Brazil's trials, half of the volunteers took the vaccine, while the other half took a placebo, Mr. Covas said. During the Phase 3 tests, 218 of the volunteers contracted Covid-19, he said, allowing scientists to calculate CoronaVac's efficacy rate by seeing how many of those people had taken the vaccine or the placebo. For definitive results, researchers were waiting for a minimum of 154 volunteers to contract Covid-19 but that figure was quickly surpassed as the number of new cases of the diseases has soared in Brazil.

About 200,000 people have now died from Covid-19 in Brazil, second only to the U.S.

Augusto Capodicasa, who manages a philanthropic hospital in the coastal city of Santos near São Paulo, said doctors were bracing for a postholiday surge in cases after many Brazilians threw parties and headed to the beach over Christmas. While the hospital has so far managed to deal with demand, Mr. Capodicasa said he feared the new wave of cases could overwhelm them. "How would I deal with the choice of whom to give a bed to?" he said. "It's the biggest fear of every hospital administrator." For the past month, Brazil has been reporting an average of more than 30,000 new cases a day.

São Paulo state Gov. João Doria said he plans to use CoronaVac to immunize the whole of the state, home to a fifth of Brazil's population, by the end of July. Brazil's Oswaldo Cruz Foundation, a medical institute, is also expected to request approval as early as Thursday from the country's regulator for emergency use of the vaccine developed by AstraZeneca PLC and Oxford University.

Miguel Cendoroglo Neto, chief medical officer of the Israelita Albert Einstein health-care group, said Brazil would have to rely on several vaccines to immunize its vast population as quickly as possible. "If the efficacy rate is lower, you need to immunize more people to reach herd immunity," he said. But CoronaVac offered a good solution for Brazil, he said, adding that its efficacy rate was still higher than many flu vaccines.

Write to Samantha Pearson at, Luciana Magalhaes at and Chao Deng at


(END) Dow Jones Newswires

January 07, 2021 15:28 ET (20:28 GMT)

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