By Carl Zimmer
When Vladimir Putin announced Tuesday that Russia had approved a coronavirus vaccine — with no evidence from large-scale clinical trials — vaccine experts were worried.
“I think it’s really scary. It’s really risky,” said Daniel Salmon, the director of the Institute for Vaccine Safety at Johns Hopkins University.
Dr. Salmon and other experts said that Russia is taking a dangerous step by jumping ahead of so-called Phase 3 trials, which can determine that the vaccine works better than a placebo and doesn’t cause harm to some people who get it.
Unlike experimental drugs given to the sick, vaccines are intended to be given to masses of healthy people. So they must clear a high bar of safety standards. If hundreds of millions of people get a vaccine, even a rare side effect could crop up in thousands of people.
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