Primary series COVID-19 vaccine effectiveness among healthcare workers in Albania, February-December 2021

Julia E Rubin-Smith; Madelyn Yiseth Rojas Castro; Iria Preza; Iris Hasibra; Jonilda Sulo; Albana Fico; Rovena Daja; Adela Vasili; Majlinda Kota; Alexis Schmid; Shela Sridhar; Alina Guseinova; Golubinka Boshevska; Gazmend Bejtja; Barbara Mühlemann; Christian Drosten; Pernille Jorgensen; Richard Pebody; Esther Kissling; Kathryn E Lafond; Mark A Katz; Silvia Bino

doi:10.1016/j.ijregi.2023.04.009

Primary series COVID-19 vaccine effectiveness among healthcare workers in Albania, February-December 2021

IJID Reg. 2023 Sep:8:19-27. doi: 10.1016/j.ijregi.2023.04.009. Epub 2023 Apr 16.

Authors

Julia E Rubin-Smith^{1

2}, Madelyn Yiseth Rojas Castro³, Iria Preza⁴, Iris Hasibra⁴, Jonilda Sulo⁵, Albana Fico⁴, Rovena Daja⁴, Adela Vasili⁴, Majlinda Kota⁴, Alexis Schmid^{1

2}, Shela Sridhar^{1

6}, Alina Guseinova⁷, Golubinka Boshevska⁷, Gazmend Bejtja⁷, Barbara Mühlemann^{8

9}, Christian Drosten^{8

9}, Pernille Jorgensen⁷, Richard Pebody⁷, Esther Kissling³, Kathryn E Lafond¹⁰, Mark A Katz⁷, Silvia Bino⁴

Affiliations

¹ Global Health Program, Boston Children's Hospital, Boston, MA, USA.
² Division of Emergency Medicine, Boston Children's Hospital, Boston, MA, USA.
³ Epiconcept, Paris, France.
⁴ Institute of Public Health, Tirana, Albania.
⁵ Southeast European Centre for Surveillance and Control of Infectious Disease, Tirana, Albania.
⁶ Department of Global Health Equity, Brigham and Women's Hospital, Boston, MA, USA.
⁷ World Health Organization Regional Office for Europe, Copenhagen, Denmark.
⁸ Institute of Virology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt - Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
⁹ German Centre for Infection Research, Partner Site Charité, Berlin, Germany.
¹⁰ Influenza Division, US Centers for Disease Control and Prevention, Atlanta, GA, USA.

Abstract

Background: Healthcare workers have experienced high rates of morbidity and mortality from coronavirus disease 2019 (COVID-19).

Methods: A prospective cohort study was conducted in three Albanian hospitals between 19 February and 14 December 2021. All participants underwent polymerase chain reaction (PCR) and serological testing at enrolment, regular serology throughout, and PCR testing when symptomatic.Vaccine effectiveness (VE) against COVID-19 and against all severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infections (symptomatic or asymptomatic) was estimated. VE was estimated using a Cox regression model, with vaccination status as a time-varying variable.

Findings: In total, 1504 HCWs were enrolled in this study; 70% had evidence of prior SARS-CoV-2 infection. VE was 65.1% [95% confidence interval (CI) 37.7-80.5] against COVID-19, 58.2% (95% CI 15.7-79.3) among participants without prior SARS-CoV-2 infection, and 73.6% (95% CI 24.3-90.8) among participants with prior SARS-CoV-2 infection. For BNT162b2 alone, VE was 69.5% (95% CI 44.5-83.2). During the period when the Delta variant was predominant, VE was 67.1% (95% CI 38.3-82.5). VE against SARS-CoV-2 infection for the full study period was 36.9% (95% CI 15.8-52.7).

Interpretation: This study found moderate primary series VE against COVID-19 among healthcare workers in Albania. These results support the continued promotion of COVID-19 vaccination in Albania, and highlight the benefits of vaccination in populations with high levels of prior infection.

Keywords: Albania; COVID-19 vaccine; Delta variant; Healthcare workers; Hybrid immunity; Vaccine effectiveness.

Abstract

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