Using serum samples routinely collected in 9144 adults from a French general population-based cohort, we identified 353 participants with a positive anti-SARS-CoV-2 IgG test, among whom 13 were sampled between November 2019 and January 2020 and were confirmed by neutralizing antibodies testing. Investigations in 11 of these participants revealed experience of symptoms possibly related to a SARS-CoV-2 infection or situations at risk of potential SARS-CoV-2 exposure. This suggests early circulation of SARS-CoV-2 in Europe.
https://link.springer.com/article/10.1007/s10654-020-00716-2