Publication date: Jul 03, 2026
Healthcare workers (HCW) have been at the frontline during the COVID-19 pandemic, with an increased risk of infection, particularly due to the emergence of the omicron variant. This study aims to assess risk factors for omicron acquisition among vaccinated HCW, comparing hybrid immunity (previous infection and vaccination) to vaccine-induced immunity alone. We took advantage of the COVID-HOP prospective cohort, which includes vaccinated HCW followed over several months, collecting detailed data on demographic characteristics, comorbidities, and professional and personal exposures to COVID-19. We analyzed factors associated with omicron acquisition after January 2022, with a focus on immunization scheme (hybrid or vaccine-induced immunity). Out of 698 HCW analyzed, 298 acquired the omicron variant. In the multivariable analysis (taking into account comorbidities, professional/personal exposure and lifestyle), the two independent factors associated with an increased risk of infection were: younger age (P = 0. 005) and immunization scheme (OR associated with vaccine-induced immunity alone: 2. 43 [95% Confidence Interval: 1. 64-3. 60]) with hybrid immunity as reference). HCW with hybrid immunity have a reduced risk of acquiring omicron compared to those with vaccine-induced immunity alone. These findings emphasize the importance of a combined vaccination strategy to better protect HCW against emerging variants, and to vaccine HCW who experienced previous COVID-19 episodes.
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| Concepts | Keywords |
|---|---|
| COVID-19 | |
| Healthcare workers | |
| Hybrid immunity | |
| SARS-CoV-2 | |
| Vaccine |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | COVID-19 pandemic |
| disease | MESH | infection |
| drug | DRUGBANK | Tropicamide |
| disease | MESH | David |
| drug | DRUGBANK | Etodolac |
| pathway | REACTOME | Reproduction |
| disease | MESH | included |
| drug | DRUGBANK | L-Citrulline |
| disease | MESH | CRB |
| drug | DRUGBANK | Diethylstilbestrol |
| disease | MESH | des |
| disease | MESH | Tumors |
| disease | MESH | breakthrough infections |
| drug | DRUGBANK | L-Isoleucine |
| drug | DRUGBANK | Ethanol |
| disease | MESH | face |
| drug | DRUGBANK | Etoperidone |
| disease | MESH | pneumonia |
| disease | MESH | fever |
| disease | MESH | asthenia |
| disease | MESH | myalgia |
| disease | MESH | headache |
| disease | MESH | cough |
| disease | MESH | dyspnea |
| disease | MESH | anosmia |
| disease | MESH | ageusia |
| drug | DRUGBANK | Oxygen |