evidence: Vaccine experts are warning the federal government against rushing out a coronavirus vaccine before testing has shown it’s both safe and effective. Decades of history show why they’re right. [...] Their concern that the FDA may be moving too quickly heightened when FDA Commissioner Dr. Steven Hahn told the Financial Times that his agency could consider an emergency use authorization (EUA) for a Covid-19 vaccine before late stage clinical trials are complete if the data show strong enough evidence it would protect people. [...] "This is one of the most ridiculous things I’ve heard this administration say," Markel said. "All it takes is one bad side effect to basically botch a vaccine program that we desperately need against this virus. It’s a prescription for disaster."