Next Article in Journal
Buprenorphine Increases HIV-1 Infection In Vitro but Does Not Reactivate HIV-1 from Latency
Previous Article in Journal
Efficient Pseudotyping of Different Retroviral Vectors Using a Novel, Codon-Optimized Gene for Chimeric GALV Envelope
Previous Article in Special Issue
Differential Influence of Age on the Relationship between Genetic Mismatch and A(H1N1)pdm09 Vaccine Effectiveness
Article

Influenza Vaccine Effectiveness in Preventing Severe Outcomes in Patients Hospitalized with Laboratory-Confirmed Influenza during the 2017–2018 Season. A Retrospective Cohort Study in Catalonia (Spain)

1
Department of Statistics and Operations Research, Polytechnic University of Catalonia/BARCELONATECH, 08028 Barcelona, Spain
2
CIBER Epidemiología Salud Pública, CIBERESP, PREVICET Program, 28029 Madrid, Spain
3
Department of Medicine, University of Barcelona, 08036 Barcelona, Spain
4
Public Health Agency of Catalonia, 08005 Barcelona, Spain
5
Public Health Agency of Barcelona, 08024 Barcelona, Spain
*
Author to whom correspondence should be addressed.
Academic Editors: Haryoung Poo and Chris Ka Pun Mok
Viruses 2021, 13(8), 1465; https://doi.org/10.3390/v13081465
Received: 11 May 2021 / Revised: 19 July 2021 / Accepted: 22 July 2021 / Published: 27 July 2021
(This article belongs to the Special Issue Pandemic H1N1 Vaccine)
Seasonal influenza is a common cause of hospital admission, especially in older people and those with comorbidities. The objective of this study was to determine influenza vaccine effectiveness (VE) in preventing intensive care admissions and shortening the length of stay (LOS) in hospitalized laboratory-confirmed influenza cases (HLCI) in Catalonia (Spain). A retrospective cohort study was carried out during the 2017–2018 season in HLCI aged ≥18 years from 14 public hospitals. Differences in means and proportions were assessed using a t-test or a chi-square test as necessary and the differences were quantified using standardized effect measures: Cohen’s d for quantitative and Cohen’s w for categorical variables. Adjusted influenza vaccine effectiveness in preventing severity was estimated by multivariate logistic regression where the adjusted VE = (1 − adjusted odds ratio) · 100%; adjustment was also made using the propensity score. We analyzed 1414 HLCI aged ≥18 years; 465 (33%) were vaccinated, of whom 437 (94%) were aged ≥60 years, 269 (57.8%) were male and 295 (63.4%) were positive for influenza type B. ICU admission was required in 214 (15.1%) cases. There were 141/1118 (12.6%) ICU admissions in patients aged ≥60 years and 73/296 (24.7%) in those aged <60 years (p < 0.001). The mean LOS and ICU LOS did not differ significantly between vaccinated and unvaccinated patients. There were 52/465 (11.2%) ICU admissions in vaccinated cases vs. 162/949 (17.1%) in unvaccinated cases. Patients admitted to the ICU had a longer hospital LOS (mean: 22.4 [SD 20.3] days) than those who were not (mean: 11.1 [SD 14.4] days); p < 0.001. Overall, vaccination was associated with a lower risk of ICU admission. Taking virus types A and B together, the estimated adjusted VE in preventing ICU admission was 31% (95% CI 1–52; p = 0.04). When stratified by viral type, the aVE was 40% for type A (95% CI -11–68; p = 0.09) and 25% for type B (95% CI -18–52; p = 0.21). Annual influenza vaccination may prevent ICU admission in cases of HLCI. A non-significantly shorter mean hospital stay was observed in vaccinated cases. Our results support the need to increase vaccination uptake and public perception of the benefits of influenza vaccination in groups at a higher risk of hospitalization and severe outcomes. View Full-Text
Keywords: influenza; intensive care unit; vaccine effectiveness; length of stay influenza; intensive care unit; vaccine effectiveness; length of stay
Show Figures

Figure 1

MDPI and ACS Style

Acosta, L.; Soldevila, N.; Torner, N.; Martínez, A.; Ayneto, X.; Rius, C.; Jané, M.; Domínguez, A.; the Influenza Surveillance Network of Catalonia, PIDIRAC. Influenza Vaccine Effectiveness in Preventing Severe Outcomes in Patients Hospitalized with Laboratory-Confirmed Influenza during the 2017–2018 Season. A Retrospective Cohort Study in Catalonia (Spain). Viruses 2021, 13, 1465. https://doi.org/10.3390/v13081465

AMA Style

Acosta L, Soldevila N, Torner N, Martínez A, Ayneto X, Rius C, Jané M, Domínguez A, the Influenza Surveillance Network of Catalonia, PIDIRAC. Influenza Vaccine Effectiveness in Preventing Severe Outcomes in Patients Hospitalized with Laboratory-Confirmed Influenza during the 2017–2018 Season. A Retrospective Cohort Study in Catalonia (Spain). Viruses. 2021; 13(8):1465. https://doi.org/10.3390/v13081465

Chicago/Turabian Style

Acosta, Lesly, Nuria Soldevila, Nuria Torner, Ana Martínez, Xavier Ayneto, Cristina Rius, Mireia Jané, Angela Domínguez, and the Influenza Surveillance Network of Catalonia, PIDIRAC. 2021. "Influenza Vaccine Effectiveness in Preventing Severe Outcomes in Patients Hospitalized with Laboratory-Confirmed Influenza during the 2017–2018 Season. A Retrospective Cohort Study in Catalonia (Spain)" Viruses 13, no. 8: 1465. https://doi.org/10.3390/v13081465

Find Other Styles
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Back to TopTop