I am not talking of tests in 2019. I'm talking of the tests done in 2020 after, well, tests became available. If Covid had been growing exponentially in Europe

I am not talking of tests in 2019. I'm talking of the tests done in 2020 after, well, tests became available. If Covid had been growing exponentially in Europe for the latter part of 2019, the tests would have found massive amounts of infections. They didn't. Likewise the after the fact findings of antibodies in blood samples would show an exponential growth. Neither of the studies you linked to shows that. The Just look at the numbers from that Italy study. They're claiming that 10% of their sample had already had Covid on September 2019. "Exponential growth starts slowly" doesn't explain that. But somehow that went unnoticed and caused no detectable blip in the mortality rate, while a few months later an outbreak that could be tracked to a single event decimated the elderly in Lombardy. It's noteworthy that neither of these studies tried analyzing blood samples from say the winter of 2018 to establish a definite baseline. But if they'd done that, they probably wouldn't have much of an article to write. "We found the expected level of false positives from this test" isn't exactly newsworthy.