Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 Jan 26;12(3):961.
doi: 10.3390/jcm12030961.

SARS-CoV-2 Vaccination and Clinical Presentation of COVID-19 in Patients Hospitalized during the Delta- and Omicron-Predominant Periods

Daša Stupica  1   2 , Stefan Collinet-Adler  3 , Nataša Kejžar  4 , Mario Poljak  5 , Tina Štamol  5
Affiliations

SARS-CoV-2 Vaccination and Clinical Presentation of COVID-19 in Patients Hospitalized during the Delta- and Omicron-Predominant Periods

Daša Stupica et al. J Clin Med. .

Abstract

Evidence suggests that monovalent vaccine formulations are less effective against the Omicron SARS-CoV-2 than against previous variants. In this retrospective cohort study of hospitalized adults with PCR-confirmed COVID-19 during the Delta (October-November 2021) and Omicron (January-April 2022) variant predominant periods in Slovenia, we assessed the association between primary vaccination against SARS-CoV-2 and progression to critically severe disease (mechanical ventilation or death). Compared with the 529 patients hospitalized for acute COVID-19 during the Delta period (median age 65 years; 58.4% men), the 407 patients hospitalized during the Omicron period (median age 75 years; 50.6% men) were older, more often resided in long-term care facilities, and had higher Charlson comorbidity index scores. After adjusting for age, sex, the Charlson comorbidity index, the presence of immunocompromising conditions, and vaccination status, the patients admitted during the Omicron period had comparable odds of progressing to critically severe disease to those admitted during the Delta period. The 334/936 (35.7%) patients completing at least primary vaccination had lower odds of progression to critically severe disease and shorter hospital stay than unvaccinated patients; however, the protective effect of vaccination was less pronounced during the Omicron than during the Delta period. Although the Omicron variant appeared to better evade immunity induced by monovalent vaccines than the Delta variant, vaccination against SARS-CoV-2 remained an effective intervention to decrease morbidity and mortality in COVID-19 patients infected with the Omicron variant.

Keywords: COVID-19 vaccine; SARS-CoV-2 antibodies; vaccine breakthrough.

PubMed Disclaimer

Conflict of interest statement

The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. D.S. received support to speak at educational events sponsored by Merck & Co., Sanofi, and Medison Pharma. Other authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flow diagram.
Figure 2
Figure 2
Modeled probability of progression to critically severe disease during the Delta and Omicron periods by vaccination status (vaccinated vs. unvaccinated) and age in years, as assessed from logistic regression model for two male patients with COVID-19, Charlson comorbidity index 4, and without immunocompromising conditions.
See this image and copyright information in PMC

References

    1. Shrotri M., Krutikov M., Palmer T., Giddings R., Azmi B., Subbarao S., Fuller C., Irwin-Singer A., Davies D., Tut G., et al. Vaccine effectiveness of the first dose of ChAdOx1 nCoV-19 and BNT162b2 against SARS-CoV-2 infection in residents of long-term care facilities in England (VIVALDI): A prospective cohort study. Lancet Infect. Dis. 2021;21:1529–1538. doi: 10.1016/S1473-3099(21)00289-9. - DOI - PMC - PubMed
    1. Dagan N., Barda N., Kepten E., Miron O., Perchik S., Katz M.A., Hernán M.A., Lipsitch M., Reis B., Balicer R.D. BNT162b2 mRNA COVID-19 Vaccine in a Nationwide Mass Vaccination Setting. N. Engl. J. Med. 2021;384:1412–1423. doi: 10.1056/NEJMoa2101765. - DOI - PMC - PubMed
    1. Baden L.R., El Sahly H.M., Essink B., Kotloff K., Frey S., Novak R., Diemert D., Spector S.A., Rouphael N., Creech C.B., et al. Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine. N. Engl. J. Med. 2021;384:403–416. doi: 10.1056/NEJMoa2035389. - DOI - PMC - PubMed
    1. Sadoff J., Le Gars M., Shukarev G., Heerwegh D., Truyers C., de Groot A.M., Stoop J., Tete S., Van Damme W., Leroux-Roels I., et al. Interim Results of a Phase 1–2a Trial of Ad26.COV2.S COVID-19 Vaccine. N. Engl. J. Med. 2021;384:1824–1835. doi: 10.1056/NEJMoa2034201. - DOI - PMC - PubMed
    1. Juthani P.V., Gupta A., Borges K.A., Price C.C., Lee A.I., Won C.H., Chun H.J. Hospitalisation among vaccine breakthrough COVID-19 infections. Lancet Infect. Dis. 2021;21:1485–1486. doi: 10.1016/S1473-3099(21)00558-2. - DOI - PMC - PubMed

LinkOut - more resources