CAJICA, Colombia – Brazil's Butantan Institute and the government of the state of Sao Paulo released efficacy results on Jan. 7 for Coronavac, developed by China’s Sinovac Biotech Ltd., that suggest the COVID-19 vaccine is more than 78% effective.

Butantan will manufacture and distribute the vaccine in Brazil and other countries in Latin America after having completed phase III trials involving 12,476 participants from the health care sector in 16 centers across eight states.

“The Butantan vaccine has a range of efficacy that goes from 78% to 100% in mild, moderate and severe cases,” said Butantan’s Director Dimas Covas during a press conference in Sao Paulo after a meeting with Anvisa, the Brazilian health care regulator.

“The vaccine protected 100% of the participants in relation to severe COVID-19 cases. It protected 100% of the participants in relation to moderate cases in the high-risk population,” said Covas. “Not even a single volunteer of those who received the vaccine, required to be admitted at a hospital.”

Mild cases were prevented at a 78% rate with some 22% of participants requiring outpatient care after showing mild symptoms of COVID-19.

In phase I/II trials, Coronavac was found to be safe and induce antibody responses within 28 days of immunization when given in two doses, 14 days apart.

Delayed communication

The issue of which vaccine or vaccines will be used across Brazil or in independent states has been politically charged. President Jair Bolsonaro has pinned his hopes on AZD-1222, developed by Astrazeneca plc and the University of Oxford and now called COVID-19 Vaccine Astrazeneca. State governors, like Sao Paulo Governor Joao Doria and others, have placed their bets on Coronavac or other Chinese vaccines or Sputnik V, developed by Russia’s Gameleya National Center of Epidemiology and Microbiology.

The release of the phase III results for Coronavac was delayed on Dec. 23, 2020, when Butantan said the vaccine had shown more than 50% efficacy but that Sinovac asked for two more weeks to analyze the results of trials in different countries, including Brazil, Turkey, Indonesia and Chile. With different trial formats, the results have varied.

“They were scheduled to be released to the press in the second week of December, but the government of Sao Paulo decided not to do so given the differences in the figures registered in Turkey,” Igor Patrick, the Rio de Janeiro-based director of communications at Observa China, an independent network of Portuguese-speaking sinologists, told BioWorld.

“It was a highly criticized decision in the Brazilian press last month and many medical experts said that canceling the release of the efficacy results was a serious communication mistake by the Butantan Institute,” he said.

“I have no doubt that Anvisa will approve Coronavac. The pressure on Bolsonaro to start vaccination is already very high and would worsen considerably if the population perceived political motivations regarding the approval of (vaccines) in Brazil,” said Patrick.

Confident in approval

“Anvisa understood and was positive on the results,” said Covas at the press conference. “We need this vaccine to reach the arms of the people... We are confident in the approval through the emergency pathway.”

Anvisa announced an emergency pathway to approve COVID-19 vaccines in early December. Some regulatory experts were not expecting the Chinese company to use the emergency pathway, but rather the regular one.

A second meeting with Anvisa was scheduled for the evening of Thursday, Jan. 7, and an application was likely to be submitted by Friday, Jan. 8, at the latest.

“This is the toughest trial for a COVID-19 vaccine in the world and this is the most complete trial ever disclosed,” said Covas. “Other vaccines have been trialed with people with less risk exposure to the virus,” he said.

The Butantan Institute has already received enough supplies to produce 10.8 million doses of Coronavac.