"It is not the best vaccine in the world." So said a Brazilian microbiologist of a vaccine created by China that the developing world had held high hopes on. Scientists with the Butantan Institute in Sao Paulo on Tuesday said late-stage trials established the efficacy rate of the CoronaVac vaccine made by Sinovac of Beijing is 50.38%, reports CNN. That doesn't mean it's unusable, as it meets the WHO's minimum requirements, but that it would take longer for a country to achieve herd immunity. And it dims the hopes developing countries had for the vaccine, which doesn't require the extreme cold storage that Pfizer and Moderna's versions, which have a roughly 95% efficacy rate, do. Context from the Wall Street Journal: "From Latin America to Africa and Asia, many developing countries have pinned their hopes on CoronaVac and other Chinese vaccine candidates as richer nations snap up inoculations developed in the West."
The New York Times reports that the technology that underpins the CoronaVac vaccine could be to blame. Sinovac used a legacy approach in which the virus is treated with chemicals that weaken or kill it; the vaccine is made up of the virus that results from the process and should cause the body to produce antibodies. The Times explains the rub: "But the process of killing the virus can weaken a vaccine's potency, resulting in an immune response that could be shorter or less effective." The Journal reports on another thorn in the news: Results released last week from the Butantan Institute put the efficacy rate at 78%. But Brazilian scientists—bothered by delays and a perceived lack of transparency about the data—kept pressing the company, which on Tuesday said the 78% figure didn't include those who experienced "very mild" cases that required no treatment. Reuters reports Brazil has signed off on a deal to buy up to 100 million doses of the vaccine. (More coronavirus vaccine stories.)
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