Brazil. The coronavirus vaccine developed by Sinovac Biotech in China has an effectiveness of only 50.4% in preventing symptomatic infections according to a Brazilian study, researchers said on Tuesday, according to Reuters.
The effectiveness of the Chinese vaccine is on the verge of approval and is well below the rate announced last week.
The latest results are a major disappointment for Brazil, as the Chinese vaccine is one of two vaccines the federal government has purchased to begin immunization during the world’s second COVID-19.
Scientists and observers at the Butantan Center are sharply criticized for the partial data published just a few days ago, which generated unrealistic expectations. Confusion could be added to Brazil’s skepticism about the Chinese vaccine, which President Jair Bolsonaro has criticized, questioning its “origins.”
“We have a good vaccine. It is not the best vaccine in the world. Not the ideal vaccine, “said microbiologist Natalia Pasternak, criticizing Butantan’s triumphant tone.
Last week, Brazilian researchers celebrated results showing a 78% efficacy against “mild to severe” COVID-19 cases, a rate they later described as “clinical efficacy”.
Meanwhile, experts say that vaccines developed by Chinese manufacturers are not subject to the same public scrutiny as alternatives in the US and Europe.
Ricardo Palacios, medical director at the Butantan biomedical center in Sao Paulo, said the new figure includes infections classified as “very mild” because they do not require clinical care.
Moreover, researchers in Butantan postponed the announcement of their results three times, accusing a confidentiality clause in a contract with Sinovac.
Turkish researchers said last month that CoronaVac developed by Sinovac has an efficiency of 91.25%, following an intermediate analysis. At the same time, Indonesia approved the emergency use of the vaccine on Monday, based on interim data showing that it is 65% effective.
Butantan officials said the design of the Brazilian study, focusing on early-stage health workers during a severe outbreak in Brazil and including elderly volunteers, made it impossible to compare the results directly with other studies or vaccines.
Brazil’s national immunization program is currently based on CoronaVac produced by Sinovac and the vaccine developed by Oxford University and AstraZeneca Plc, but none of them have received regulatory approval in Brazil.
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