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Published on: December 1, 2017
COVID-19-Associated Hospitalizations Among Vaccinated and Unvaccinated Adults 18 Years or Older in 13 US States,
Fiona P Havers1,2, Huong Pham1, Christopher A Taylor1
1US Centers for Disease Control and Prevention COVID-19 Response, Atlanta, Georgia.
Insights
COVID-19 hospitalization rates were significantly higher in unvaccinated individuals compared to vaccinated ones. Booster doses were associated with the lowest hospitalization rates, underscoring the importance of vaccination for public health.
Area of Science:
- Epidemiology
- Infectious Diseases
- Public Health
Background:
- Understanding COVID-19 hospitalization risk factors in vaccinated individuals is crucial for public health.
- Assessing the association between COVID-19 vaccines and hospitalization rates informs control strategies.
Purpose of the Study:
- To determine characteristics of COVID-19 hospitalizations among vaccinated persons.
- To compare hospitalization rates between unvaccinated and vaccinated individuals.
Main Methods:
- A cross-sectional study analyzed data from over 250 hospitals in the US from January 2021 to April 2022.
- Linked state immunization data to identify vaccination status and compared hospitalization rates.
- Detailed medical record review compared characteristics of vaccinated and unvaccinated hospitalized patients.
Main Results:
- Unvaccinated individuals had 3.5 to 17.7 times higher COVID-19 hospitalization rates than vaccinated individuals.
- During Omicron predominance, unvaccinated individuals had 10.5 times higher rates, and those without a booster had 2.5 times higher rates than boosted individuals.
- Hospitalized vaccinated patients were older and more likely to have multiple underlying conditions compared to unvaccinated patients.
Conclusions:
- Unvaccinated adults face a higher risk of COVID-19 hospitalization.
- Booster doses significantly reduce hospitalization rates.
- Promoting vaccination, including all recommended doses, remains essential for public health practitioners.
Importance:
Understanding risk factors for hospitalization in vaccinated persons and the association of COVID-19 vaccines with hospitalization rates is critical for public health efforts to control COVID-19.
Objective:
To determine characteristics of COVID-19-associated hospitalizations among vaccinated persons and comparative hospitalization rates in unvaccinated and vaccinated persons.
Design, Setting, And Participants:
From January 1, 2021, to April 30, 2022, patients 18 years or older with laboratory-confirmed SARS-CoV-2 infection were identified from more than 250 hospitals in the population-based COVID-19-Associated Hospitalization Surveillance Network. State immunization information system data were linked to cases, and the vaccination coverage data of the defined catchment population were used to compare hospitalization rates in unvaccinated and vaccinated individuals. Vaccinated and unvaccinated patient characteristics were compared in a representative sample with detailed medical record review; unweighted case counts and weighted percentages were calculated.
Exposures:
Laboratory-confirmed COVID-19-associated hospitalization, defined as a positive SARS-CoV-2 test result within 14 days before or during hospitalization.
Main Outcomes And Measures:
COVID-19-associated hospitalization rates among vaccinated vs unvaccinated persons and factors associated with COVID-19-associated hospitalization in vaccinated persons were assessed.
Results:
Using representative data from 192 509 hospitalizations (see Table 1 for demographic information), monthly COVID-19-associated hospitalization rates ranged from 3.5 times to 17.7 times higher in unvaccinated persons than vaccinated persons regardless of booster dose status. From January to April 2022, when the Omicron variant was predominant, hospitalization rates were 10.5 times higher in unvaccinated persons and 2.5 times higher in vaccinated persons with no booster dose, respectively, compared with those who had received a booster dose. Among sampled cases, vaccinated hospitalized patients with COVID-19 were older than those who were unvaccinated (median [IQR] age, 70 [58-80] years vs 58 [46-70] years, respectively; P < .001) and more likely to have 3 or more underlying medical conditions (1926 [77.8%] vs 4124 [51.6%], respectively; P < .001).
Conclusions And Relevance:
In this cross-sectional study of US adults hospitalized with COVID-19, unvaccinated adults were more likely to be hospitalized compared with vaccinated adults; hospitalization rates were lowest in those who had received a booster dose. Hospitalized vaccinated persons were older and more likely to have 3 or more underlying medical conditions and be long-term care facility residents compared with hospitalized unvaccinated persons. The study results suggest that clinicians and public health practitioners should continue to promote vaccination with all recommended doses for eligible persons.
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