Piecemeal disclosures about Chinese vaccine trials globally have raised concerns that they are not subject to the same public scrutiny as American and European alternatives. Palacios and officials from the São Paulo state government, which funds Butantan, emphasized the good news that none of the volunteers vaccinated with CoronaVac had to be hospitalized with symptoms of COVID-19. Public health experts said that will only come as a relief to Brazilian hospitals that are collapsing under pressure from the growing number of cases. However, it will take longer to curb the pandemic with a vaccine that allows so many mild cases. “It is a vaccine that will start the process of overcoming the pandemic,” Pasternak said.
The Butantan researchers delayed announcing their results three times, blaming a confidentiality clause in a contract with Sinovac. Meanwhile, Turkish researchers said last month that CoronaVac was 91.25% effective according to an interim analysis. Indonesia on Monday approved emergency use of the vaccine based on interim data showing it is 65% effective. Butantan officials said the design of the Brazilian study, which focuses on front-line health workers during a severe outbreak in Brazil and includes elderly volunteers, made it impossible to compare the results directly with other trials or vaccines.
Still, the COVID-19 vaccines in use by Pfizer Inc with its partner BioNTech SE and Moderna Inc were shown to be approximately 95% effective in preventing disease in their leading late-stage trials. The disappointing data from CoronaVac is the latest setback for vaccination efforts in Brazil, where more than 200,000 people have died since the outbreak began, the worst death toll outside the United States. Brazil’s national immunization program is currently based on CoronaVac and the vaccine developed by the University of Oxford and AstraZeneca Plc, neither of which has received regulatory approval in Brazil.
Anvisa, which has stipulated an efficacy rate of at least 50% for vaccines in the pandemic, has already lobbied Butantan for more details of its study, after it requested authorization for emergency use on Friday. The regulator said it will meet on Sunday to decide on emergency use requests for CoronaVac and the British vaccine. AstraZeneca was unable to deliver active ingredients to Brazil over the weekend, leaving the government scrambling to import finished doses of the vaccine from India to begin inoculations.
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