Continuous population-level monitoring of SARS-CoV-2 seroprevalence in a large European metropolitan region.
Emmenegger M., De Cecco E., Lamparter D., Jacquat RPB., Riou J., Menges D., Ballouz T., Ebner D., Schneider MM., Morales IC., Doğançay B., Guo J., Wiedmer A., Domange J., Imeri M., Moos R., Zografou C., Batkitar L., Madrigal L., Schneider D., Trevisan C., Gonzalez-Guerra A., Carrella A., Dubach IL., Xu CK., Meisl G., Kosmoliaptsis V., Malinauskas T., Burgess-Brown N., Owens R., Hatch S., Mongkolsapaya J., Screaton GR., Schubert K., Huck JD., Liu F., Pojer F., Lau K., Hacker D., Probst-Müller E., Cervia C., Nilsson J., Boyman O., Saleh L., Spanaus K., von Eckardstein A., Schaer DJ., Ban N., Tsai C-J., Marino J., Schertler GFX., Ebert N., Thiel V., Gottschalk J., Frey BM., Reimann RR., Hornemann S., Ring AM., Knowles TPJ., Puhan MA., Althaus CL., Xenarios I., Stuart DI., Aguzzi A.
Effective public-health measures against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against three SARS-CoV-2 proteins. We used TRABI for continuous seromonitoring of hospital patients and blood donors (n=72'250) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). We found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19. Crucially, we found no evidence for a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2-infected subjects represents a resource for the study of chronic and possibly unexpected sequelae.