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. 2021 Nov;53(11):876-879.
doi: 10.1080/23744235.2021.1945139. Epub 2021 Jun 26.

Transmission of SARS-CoV-2 variant B.1.1.7 among vaccinated health care workers

Petros Ioannou  1 , Stamatis Karakonstantis  1 , Eirini Astrinaki  2 , Stamatina Saplamidou  2 , Efsevia Vitsaxaki  2 , Georgios Hamilos  3 , George Sourvinos  4 , Diamantis P Kofteridis  1
Affiliations

Transmission of SARS-CoV-2 variant B.1.1.7 among vaccinated health care workers

Petros Ioannou et al. Infect Dis (Lond). 2021 Nov.

Abstract

Background: Vaccination against COVID-19 is among the most effective measures to stop the spread of the disease. However, acceptance of vaccination against COVID-19 among HCWs has not been universal and emergence of new variants with increased transmissibility, reduced neutralization by BNT162b2 vaccine-elicited sera and ability to cause breakthrough infections in vaccinated individuals is concerning. The aim of this study was to compare viral load, clinical presentation at diagnosis and type of exposure among vaccinated (with BNT162b2) and non-vaccinated healthcare workers (HCWs).

Methods: Prospective cohort of HWCs diagnosed with COVID-19 by nasopharyngeal PCR from 4 January to 14 April. Viral loads were expressed by the cycle threshold (Ct) in PCR.

Results: During the study period 55 HCWs were found positive for SARS-CoV-2, most of whom (44/55) were identified from March 28 to April 14 during an in-hospital COVID-19 outbreak. Of the 55 HCWs, 21 were fully vaccinated and another three had received one dose. Most cases (54/55) were due to variant B.1.1.7. Vaccinated and unvaccinated HCWs did not differ significantly in regards to age, gender, site of acquisition, presence of symptoms at diagnosis and viral load.

Conclusions: This study found a similar viral load in vaccinated and non-vaccinated HCWs infected by SARS-CoV-2 variant B.1.1.7, suggesting potentially reduced efficacy of BNT162b2 in preventing transmission of B.1.1.7.

Keywords: COVID-19; SARS-CoV-2; vaccination.

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Conflict of interest statement

DPK reports lecture honoraria from Pfizer, MSD, ViiV and Angelini. The rest of the authors have no conflict of interest.

References

    1. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus-Infected Pneumonia in Wuhan, China. Jama. 2020;323(11):1061–1069. - PMC - PubMed
    1. Rivett L, Sridhar S, Sparkes D, et al. Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission. Elife. 2020; 11:9. - PMC - PubMed
    1. Forni G, Mantovani A.. COVID-19 vaccines: where we stand and challenges ahead. Cell Death Differ. 2021;28(2):626–639. - PMC - PubMed
    1. Gagneux-Brunon A, Detoc M, Bruel S, et al. Intention to get vaccinations against COVID-19 in French healthcare workers during the first pandemic wave: a cross-sectional survey. J Hosp Infect. 2021;108:168–173. - PMC - PubMed
    1. Verger P, Scronias D, Dauby N, et al. Attitudes of healthcare workers towards COVID-19 vaccination: a survey in France and French-speaking parts of Belgium and Canada. Euro Surveill. 2020;2021:26. - PMC - PubMed