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Evolution of seroprevalence to SARS-CoV-2 in blood donors in Sarajevo Canton, Federation of Bosnia and Herzegovina: cross-sectional and longitudinal studies
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  • Sanjin Musa,
  • Elma Catovic Baralija,
  • Veronica Ivey Sawin,
  • Anthony Nardone,
  • Mirza Palo,
  • Sinisa Skocibusic,
  • Mia Blazevic,
  • Seila Cilovic Lagarija,
  • Gorana Ahmetovic-Karic,
  • Alma Ljuca,
  • Sanela Dostovic-Halilovic,
  • Rozalija Nedic,
  • Lorenzo Subissi,
  • Rawi Ibrahim,
  • Golubinka Boshevska,
  • Isabel Bergeri,
  • Richard Pebody,
  • Aisling VAUGHAN
Sanjin Musa
Institute of Public Health of the Federation of Bosnia and Herzegovina

Corresponding Author:sanjinm@yahoo.com

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Elma Catovic Baralija
Institute for Transfusion Medicine of the Federation of Bosnia and Herzegovina
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Veronica Ivey Sawin
Institute of Public Health of the Federation of Bosnia and Herzegovina
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Anthony Nardone
Epiconcept SAS
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Mirza Palo
World Health Organization Office in Bosnia and Herzegovina
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Sinisa Skocibusic
Institute of Public Health of the Federation of Bosnia and Herzegovina
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Mia Blazevic
Institute of Public Health of the Federation of Bosnia and Herzegovina
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Seila Cilovic Lagarija
Institute of Public Health of the Federation of Bosnia and Herzegovina
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Gorana Ahmetovic-Karic
Institute for Transfusion Medicine of the Federation of Bosnia and Herzegovina
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Alma Ljuca
Institute for Transfusion Medicine of the Federation of Bosnia and Herzegovina
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Sanela Dostovic-Halilovic
Institute for Transfusion Medicine of the Federation of Bosnia and Herzegovina
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Rozalija Nedic
Institute of Public Health of the Federation of Bosnia and Herzegovina
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Lorenzo Subissi
World Health Organization
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Rawi Ibrahim
World Health Organization Regional Office for Europe
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Golubinka Boshevska
World Health Organization Regional Office for Europe
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Isabel Bergeri
World Health Organization
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Richard Pebody
World Health Organization Regional Office for Europe
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Aisling VAUGHAN
World Health Organization Regional Office for Europe
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Abstract

Background Sarajevo Canton in the Federation of Bosnia and Herzegovina has recorded several waves of high SARS-CoV-2 transmission and has struggled to reach adequate vaccination coverage. We describe the evolution of infection- and vaccine-induced SARS-CoV-2 antibody response and persistence. Methods We conducted repeated cross-sectional analyses of blood donors aged 18-65 years in Sarajevo Canton in November-December 2020 and 2021. We analyzed serum samples for anti-nucleocapsid (anti-N) and anti-spike (anti-S) antibodies. To assess immune durability, we conducted longitudinal analyses of seropositive participants at 6 and 12 months. Results 1015 participants were included in Phase 1 (November-December 2020), and 1152 in Phase 2 (November-December 2021). Seroprevalence increased significantly from 19.2% (95% CI: 17.2-21.4%) in Phase 1 to 91.6% (95% CI: 89.8-93.1%) in Phase 2. Anti-S IgG titers were significantly higher among vaccinated (58.5%) than unvaccinated infected participants across vaccine products (p<0.001), though highest among those who received an mRNA vaccine. At 6 months, 78/82 (95.1%) participants maintained anti-spike seropositivity; at 12 months, 58/58 (100.0%) participants were seropositive and 33 (56.9%) had completed the primary vaccine series within 6 months. Among 11 unvaccinated participants who were not reinfected at 12 months, anti-S IgG declined from median 770.1 (IQR 615.0-1321.7) to 290.8 (IQR 175.7-400.3). Anti-N IgG antibodies waned earlier; from 35.4% seropositive at 6 months to 24.1% at 12 months. Conclusions SARS-CoV-2 seroprevalence increased significantly over 12 months from end of 2020 to end of 2021. Although individuals with previous infection may have residual protection, COVID-19 vaccination is vital to strengthening population immunity.
14 Oct 2022Submitted to Influenza and other respiratory viruses
18 Oct 2022Submission Checks Completed
18 Oct 2022Assigned to Editor
25 Nov 2022Reviewer(s) Assigned
21 Apr 2023Review(s) Completed, Editorial Evaluation Pending
03 May 2023Editorial Decision: Revise Major
29 Jun 20231st Revision Received
04 Jul 2023Submission Checks Completed
04 Jul 2023Assigned to Editor
13 Jul 2023Reviewer(s) Assigned
21 Jul 2023Review(s) Completed, Editorial Evaluation Pending
23 Jul 2023Editorial Decision: Accept