Restrictions on social contact stemmed disease spread, but weighing up the ultimate costs and benefits of lockdown measures is a challenge.

In March 2021, a doctor in Brazil named Ricardo Savaris published a now-discredited research paper that went viral on social media¹.

It had been a year since the first wave of the COVID-19 pandemic forced governments to apply the desperate measures collectively known as lockdowns — cancelling sporting and cultural events, closing retail outlets, restaurants, schools and universities, and ordering people to stay at home. At the time, countries were once again dialling lockdown policies up or down, as the Alpha variant of the coronavirus SARS-CoV-2 surged in different places.

Lockdown measures did what they were supposed to. When they were enforced rigorously enough to reduce people’s social contacts sharply, they shrank COVID-19 outbreaks; several studies had demonstrated this.