The claims that caused lockdowns were 3-10% death rate.
The world was brought to a standstill primarily due to massive fearmongering. The earliest high rates came from three things: Conflation of "infection" and "case", rationing of tests to people doctors were already pretty sure had been exposed (suppressing the denominator and inflating the rate), and biased samples (for example the Diamond Princess cruise ship was weighted towards the most susceptible population and maxed out 1.2% a month after the lockdowns had begun).