Low awareness of past SARS-CoV-2 infection in healthy plasma donors

van den Hurk, Katja; Merz, Eva-Maria; Prinsze, Femmeke J.; Spekman, Marloes L.C.; Quee, Franke A.; Ramondt, Steven; Slot, Ed; Vrielink, Hans; Huis in ’t Veld, Elisabeth M.J.; Zaaijer, Hans L.; Hogema, Boris M.

Awareness of infection with SARS-CoV-2 is crucial for the effectiveness of COVID-19 control measures. Here, we investigate awareness of infection and symptoms in relation to antibodies against SARS-CoV-2 in healthy plasma donors. We ask individuals donating plasma across the Netherlands between May 11th and 18th 2020 to report COVID-19 related symptoms and we test for antibodies indicative of a past infection with SARS-CoV-2. Among 3,676 with antibody and questionnaire data 239 (6.5%) are positive for SARS-CoV-2 antibodies. Of those, 48% suspect no COVID-19 despite the majority reporting symptoms. 11% of seropositive individuals report no, and 27% very mild symptoms at any time during the first peak of the epidemic. Anosmia/ageusia and fever are most strongly associated with seropositivity. Almost half of seropositive individuals do not suspect SARS-CoV-2 infection. Improved recognition of COVID-19 symptoms, in particular anosmia/ageusia and fever, is needed to reduce widespread SARS-CoV-2 transmission.