Unexpected detection of SARS-CoV-2 antibodies in the prepandemic period in Italy

[Hoopoe]

We investigated the presence of SARS-CoV-2 receptor-binding domain (RBD)–specific antibodies in blood samples of 959 asymptomatic individuals enrolled in a prospective lung cancer screening trial between September 2019 and March 2020 to track the date of onset, frequency, and temporal and geographic variations across the Italian regions. SARS-CoV-2 RBD-specific antibodies were detected in 111 of 959 (11.6%) individuals, starting from September 2019 (14%), with a cluster of positive cases (>30%) in the second week of February 2020 and the highest number (53.2%) in Lombardy.

https://journals.sagepub.com/doi/abs/10.1177/0300891620974755?journalCode=tmja

 

[Snow Leopard]

Serological tests like this have known limitations in specificity and there is also a risk of contamination, however unlikely.

But the biggest limitation is the fact they didn't bother to confirm with PCR testing - without doing so, this study is sloppy and unconvincing.

If the study was published in a preprint in March/April and the authors indicated they would shortly followup with PCR testing, I'd give them the benefit of the doubt, but that wasn't the case.