Eurosurv. Seroprevalence of anti-SARS-CoV-2 antibodies 6 months into the vaccination campaign in Geneva, Switzerland, 1 June to 7 July 2021

[tetano]

• Silvia Stringhini[SUP]1,2,3[/SUP] , María-Eugenia Zaballa[SUP]1[/SUP] , Nick Pullen[SUP]1[/SUP] , Javier Perez-Saez[SUP]1,4,5[/SUP] , Carlos de Mestral[SUP]1,3[/SUP] , Andrea Jutta Loizeau[SUP]1[/SUP] , Julien Lamour[SUP]1[/SUP] , Francesco Pennacchio[SUP]1[/SUP] , Ania Wisniak[SUP]1,5[/SUP] , Roxane Dumont[SUP]1[/SUP] , Hélène Baysson[SUP]1,2[/SUP] , Viviane Richard[SUP]1[/SUP] , Elsa Lorthe[SUP]1[/SUP] , Claire Semaani[SUP]1[/SUP] , Jean-François Balavoine[SUP]7[/SUP] , Didier Pittet[SUP]7,8[/SUP] , Nicolas Vuilleumier[SUP]2,6,7[/SUP] , François Chappuis[SUP]2,9[/SUP] , Omar Kherad[SUP]7,10[/SUP] , Andrew S. Azman[SUP]1,4,5[/SUP] , Klara Posfay-Barbe[SUP]7,11[/SUP] , Laurent Kaiser[SUP]6,7,12[/SUP] , Idris Guessous[SUP]2,9[/SUP] , on behalf of the Specchio-COVID19 study group[SUP]13[/SUP]

Background

Up-to-date seroprevalence estimates are critical to describe the SARS-CoV-2 immune landscape and to guide public health decisions.

AimWe estimate seroprevalence of anti-SARS-CoV-2 antibodies 15 months into the COVID-19 pandemic and 6 months into the vaccination campaign.

Methods

We conducted a population-based cross-sectional serosurvey between 1 June and 7 July 2021, recruiting participants from age- and sex-stratified random samples of the general population. We tested participants for anti-SARS-CoV-2 antibodies targeting the spike (S) or nucleocapsid (N) proteins using the Roche Elecsys immunoassays. We estimated the anti-SARS-CoV-2 antibodies seroprevalence following vaccination and/or infection (anti-S antibodies), or infection only (anti-N antibodies).

Results

Among 3,355 individuals (54.1% women; 20.8% aged < 18 years and 13.4% aged ≥ 65 years), 2,161 (64.4%) had anti-S antibodies and 906 (27.0%) had anti-N antibodies. The total seroprevalence was 66.1% (95% credible interval (CrI): 64.1–68.0). We estimated that 29.9% (95% Crl: 28.0–31.9) of the population developed antibodies after infection; the rest having developed antibodies via vaccination. Seroprevalence estimates differed markedly across age groups, being lowest among children aged 0–5 years (20.8%; 95% Crl: 15.5–26.7) and highest among older adults aged ≥ 75 years (93.1%; 95% Crl: 89.6–96.0). Seroprevalence of antibodies developed via infection and/or vaccination was higher among participants with higher educational level.

Conclusion

Most of the population has developed anti-SARS-CoV-2 antibodies, despite most teenagers and children remaining vulnerable to infection. As the SARS-CoV-2 Delta variant spreads and vaccination rates stagnate, efforts are needed to address vaccine hesitancy, particularly among younger individuals and to minimise spread among children.


full article


https://www.eurosurveillance.org/con...stract_content