In 2006, a team including D. A. Henderson — the epidemiologist who had led the campaign that eradicated smallpox — reviewed the evidence on how to control pandemic influenza. The paper advised against quarantining exposed people who were not sick, against closing borders, and against prolonged school closures, and it concluded that communities come through an epidemic best when the normal functioning of the community is disrupted least. In 2020, governments across the West did close to the opposite. Those who defended the 2020 measures answer that COVID-19 was not influenza: it spread from people with no symptoms, it was far more lethal to the old, and for a year there was no vaccine. Those who objected answer that the 2006 conclusions were set aside without public argument, and that the burden of proof belonged to those departing from the standing advice. When expert advice is reversed in an emergency, who should have to justify the change, and where should that argument happen?

Shown: D. A. Henderson in 2002, a week after receiving the Presidential Medal of Freedom. Public domain. Wikimedia Commons, uploaded by Wikifier.