[Ed. – Fun with numbers]
If lockdowns really altered the course of this pandemic, then coronavirus case counts should have clearly dropped whenever and wherever lockdowns took place. The effect should have been obvious, though with a time lag. … New infections should drop on day one and be noticed about ten or eleven days from the beginning of the lockdown. By day six, the number of people with first symptoms of infection should plummet (six days is the average time for symptoms to appear). By day nine or ten, far fewer people would be heading to doctors with worsening symptoms. If COVID-19 tests were performed right away, we would expect the positives to drop clearly on day ten or eleven (assuming quick turnarounds on tests).
To judge from the evidence, the answer is clear: Mandated lockdowns had little effect on the spread of the coronavirus.