COVID-19 vaccine effectiveness among the staff of the Bologna Health Trust, Italy, December 2020-April 2021

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Chiara Giansante
Elisa Stivanello
Vincenza Perlangeli
Filippo Ferretti
Paolo Marzaroli
Muriel Assunta Musti
Lorenzo Pizzi
Davide Resi
Simona Saraceni
Paolo Pandolfi


COVID-19, vaccine effectiveness, health care workers


Background and aim:

Randomized controlled trials have shown that mRNA vaccines are highly effective in preventing SARS-CoV2 infection. We conducted a study to assess the real-world effectiveness of mRNA vaccines (Pfizer-BioNTech or Moderna) in preventing all and symptomatic SARS-CoV2 infections and COVID-19 related hospitalizations in the staff of the Bologna Health Trust (HT), Italy


We followed up retrospectively 9839 staff of the Bologna HT from December 27, 2020 to April 3, 2020 and calculated the effectiveness in partially and fully vaccinated subjects by applying a multivariable Cox proportional hazard model.


Vaccine effectiveness in preventing SARS-CoV2 infections is 85.5% (95%CI: 75.9-91.3) in the partially vaccinated and 84.8% (95%CI: 73.2-91.4) in the fully vaccinated. In preventing symptomatic infection effectiveness is 81.7% (95%CI: 62.7-91.0) in the partially and 87.1% (95%CI: 69.3-94.6) in the fully vaccinated. There were no COVID-19-related hospitalizations in the partially or fully vaccinated vs 15 hospitalization in the unvaccinated cohort.


Our results confirm the effectiveness of mRNA vaccines in a real-world setting in Northern Italy.



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