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. 2025 Jan 25:45:126615.
doi: 10.1016/j.vaccine.2024.126615. Epub 2024 Dec 25.

Relative effectiveness of the second booster COVID-19 vaccines against laboratory confirmed SARS-CoV-2 infection in healthcare workers: VEBIS HCW VE cohort study (1 October 2022-2 May 2023)

Camelia Savulescu  1 , Albert Prats-Uribe  2 , Kim Brolin  3 , Anneli Uusküla  4 , Colm Bergin  5 , Catherine Fleming  6 , Viesturs Zvirbulis  7 , Dace Zavadska  8 , Konstanty Szułdrzyński  9 , Vânia Gaio  10 , Corneliu Petru Popescu  11 , Mihai Craiu  12 , Maria Cisneros  13 , Miriam Latorre-Millán  14 , Liis Lohur  15 , Jonathan McGrath  16 , Lauren Ferguson  17 , Ilze Abolina  7 , Dagne Gravele  8 , Ausenda Machado  10 , Simin Aysel Florescu  11 , Mihaela Lazar  18 , Pilar Subirats  19 , Laura Clusa Cuesta  14 , Jacklyn Sui  16 , Claire Kenny  17 , Dainis Krievins  7 , Elza Anna Barzdina  8 , Aryse Melo  20 , Alma Gabriela Kosa  21 , Victor Daniel Miron  12 , Carmen Muñoz-Almagro  22 , Ana María Milagro  14 , Sabrina Bacci  3 , Piotr Kramarz  3 , Anthony Nardone  2 ; VEBIS HCW Study Group
Affiliations

Relative effectiveness of the second booster COVID-19 vaccines against laboratory confirmed SARS-CoV-2 infection in healthcare workers: VEBIS HCW VE cohort study (1 October 2022-2 May 2023)

Camelia Savulescu et al. Vaccine. .

Abstract

Introduction: Repeated COVID-19 booster vaccination was recommended in healthcare workers (HCWs) to maintain protection. We measured the relative vaccine effectiveness (rVE) of the second booster dose of COVID-19 vaccine compared to the first booster, against laboratory-confirmed SARS-CoV-2 infection in HCWs.

Methods: In a prospective cohort study among HCWs from 12 European hospitals, we collected nasopharyngeal or saliva samples at enrolment and during weekly/fortnightly follow-up between October 2022 and May 2023. We estimated rVE of the second versus first COVID-19 vaccine booster dose against SARS-CoV-2 infection, overall, by time since second booster and restricted to the bivalent vaccines only. Using Cox regression, we calculated the rVE as (1-hazard ratio)*100, adjusting for hospital, age, sex, prior SARS-CoV-2 infection and at least one underlying condition.

Results: Among the 979 included HCWs eligible for a second booster vaccination, 392 (40 %) received it and 192 (20 %) presented an infection during the study period. The rVE of the second versus first booster dose was -5 % (95 %CI: -46; 25) overall, 3 % (-46; 36) in the 7-89 days after receiving the second booster dose. The rVE was 11 % (-43; 45) when restricted to the use of bivalent vaccines only.

Conclusion: The bivalent COVID-19 could have reduced the risk of SARS-CoV-2 infection among HCWs by 11 %. However, we note the limitation of imprecise rVE estimates due to the proportion of monovalent vaccine used in the study, the small sample size and the study being conducted during the predominant circulation of XBB.1.5 sub-lineage. COVID-19 vaccine effectiveness studies in HCWs can provide important evidence to inform the optimal timing and the use of updated COVID-19 vaccines.

Keywords: COVID-19; COVID-19 vaccines; Europe; Healthcare workers; SARS-CoV-2; Vaccine effectiveness.

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Conflict of interest statement

Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: APU reported payment under EMA DARWIN EU project outside of the submitted work. MLM, AM, LCC reported additional support received from ISIDORe (EATRIS) Network for carrying out the local SARS-CoV-2 sequencing. CPP reported speaker fees from Pfizer and MSD. SAF reported speaker fees from and participation in Advisory board of Pfizer, MSD and Gilead. CMA reported speaker fees from MSD, Pfizer and Sanofi. JS reported support for attending ESID conference 2022 from Takeda Pharmaceutical. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Figures

Fig. 1
Fig. 1
Participating hospitals by study time, VEBIS HCW study, 1 October 2022–2 May 2023. NP – Nasopharyngeal sample.
Fig. 2
Fig. 2
Exclusion flowchart, multi-country VEBIS HCW Study, 1 Oct 2022–2 May 2023.
Fig. 3
Fig. 3
Incidence rate by month of participation in the study, vaccination status and positive sample sequenced, multi-country VEBIS HCW study, October 2022–April 2023.
See this image and copyright information in PMC

References

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