TABLE. Demographic characteristics and clinical interventions and outcomes among 7,615 nonpregnant adults aged ≥18 years hospitalized with COVID-19,* by vaccination status^† and period relative to SARS-CoV-2 B.1.617.2 (Delta) variant predominance^§ — COVID-NET, 14 states,^¶ January–August 2021.

Characteristic	Weighted % of COVID-19 hospitalizations (95% CI)
	Total hospitalizations**			Unvaccinated			Fully vaccinated
	Pre-Delta period	Delta period	p-value††	Pre-Delta period	Delta period	p-value††	Pre-Delta period	Delta period	p-value††
Total	5,951	1,664	—	4,896	1,145	—	389	393	—
Demographic characteristics§§
Age group, yrs
18–49	24.7 (23.2–26.3)	35.8 (32.1–39.5)	<0.01	26.9 (25.2–28.7)	43.6 (39.1–48.2)	<0.01	10.6 (6.8–15.4)	10.8 (7.1–15.4)	>0.99
50–64	31.2 (29.5–33.0)	30.4 (27.3–33.7)		32.4 (30.5–34.4)	33.6 (29.8–37.6)		17.2 (12.9–22.3)	18.8 (13.6–25.0)
≥65	44.1 (42.0–46.2)	33.8 (30.4–37.4)		40.6 (38.3–43.0)	22.8 (19.1–26.8)		72.2 (65.8–78.0)	70.4 (63.6–76.7)
Sex
Male	52.2 (50.2–54.3)	52.3 (48.6–55.9)	>0.99	52.4 (50.2–54.6)	50.5 (46.1–55.0)	>0.99	51.7 (43.8–59.5)	56.7 (49.3–64.0)	>0.99
Female	47.8 (45.7–49.8)	47.7 (44.1–51.4)		47.6 (45.4–49.8)	49.5 (45.0–53.9)		48.3 (40.5–56.2)	43.3 (36.0–50.7)
Race/Ethnicity ¶¶
White	50.0 (47.9–52.0)	47.8 (44.1–51.6)	>0.99	48.5 (46.2–50.8)	45.4 (40.9–49.9)	>0.99	65.7 (57.7–73.1)	57.2 (49.2–65.0)	>0.99
Black	28.5 (26.6–30.5)	32.1 (28.5–35.9)		29.6 (27.5–31.8)	34.0 (29.6–38.7)		16.6 (10.4–24.6)	23.5 (16.8–31.3)
AI/AN	1.1 (0.8–1.4)	1.3 (0.8–2.0)		1.0 (0.7–1.3)	1.2 (0.6–2.1)		1.2 (0.4–2.9)	1.7 (0.6–3.7)
A/PI	6.8 (5.6–8.2)	5.4 (3.4–8.1)		7.1 (5.7–8.6)	5.0 (2.7–8.3)		5.5 (2.5–10.2)	6.8 (2.8–13.5)
Hispanic	13.6 (12.3–15.0)	13.4 (10.9–16.2)		13.8 (12.4–15.4)	14.4 (11.3–18.0)		11.0 (7.3–15.7)	10.8 (6.4–16.8)
Long-term care facility resident***
Yes	7.8 (6.5–9.1)	3.2 (2.1–4.5)	<0.01	5.9 (4.7–7.3)	1.6 (0.7–3.0)†††	<0.01	16.7 (11.4–23.2)	8.3 (4.9–12.9)	0.59
No	92.2 (90.9–93.5)	96.8 (95.5–97.9)		94.1 (92.7–95.3)	98.4 (97.0–99.3)		83.3 (76.8–88.6)	91.7 (87.1–95.1)
Hospitalization interventions and outcomes, by age group, yrs§§§
ICU admission ¶¶¶
≥18	20.1 (18.5–21.9)	23.4 (20.4–26.6)	>0.99	20.1 (18.3–21.9)	22.6 (19.1–26.3)	>0.99	19.9 (14.2–26.6)	24.6 (18.2–32.0)	>0.99
18–49	17.1 (14.6–19.9)	17.1 (12.7–22.3)	>0.99	16.8 (14.2–19.6)	16.5 (11.7–22.2)	>0.99	—****	32.0 (16.5–51.1)††††	>0.99
50–64	21.4 (18.9–24.1)	27.8 (22.6–33.5)	>0.99	21.4 (18.7–24.4)	27.8 (22.2–34.0)	>0.99	18.4 (10.2–29.4)	—****	>0.99
≥65	21.0 (18.1–24.1)	26.2 (20.7–32.3)	>0.99	21.1 (17.8–24.8)	26.7 (18.8–35.9)	>0.99	19.6 (12.7–28.2)	24.2 (16.5–33.4)	>0.99
Invasive mechanical ventilation§§§§
≥18	11.5 (10.1–12.9)	11.2 (9.1–13.7)	>0.99	11.6 (10.1–13.1)	11.3 (8.8–14.2)	>0.99	9.4 (5.2–15.3)	12.7 (7.6–19.5)	>0.99
18–49	10.1 (8.1–12.4)	7.1 (4.2–10.9)	>0.99	9.7 (7.7–12.1)	7.2 (4.2–11.6)	>0.99	—****	7.4 (1.4–21.0)†††	>0.99
50–64	11.7 (9.8–13.9)	14.5 (10.7–19.1)	>0.99	11.7 (9.6–14.0)	16.7 (12.0–22.2)	>0.99	—****	7.0 (2.0–16.8)†††	>0.99
≥65	12.1 (9.7–14.8)	12.6 (8.7–17.6)	>0.99	12.7 (10.0–15.9)	11.2 (6.6–17.5)	>0.99	7.7 (3.3–15.0)	15.0 (8.3–24.3)	>0.99
In-hospital death ¶¶¶¶
≥18	8.6 (7.5–9.9)	9.9 (7.9–12.2)	>0.99	8.2 (7.0–9.5)	8.7 (6.6–11.1)	>0.99	7.2 (4.3–11.1)	13.9 (8.7–20.7)	>0.99
18–49	3.4 (2.2–5.0)	2.0 (0.7–4.3)†††	>0.99	3.2 (2.0–4.9)	2.1 (0.7–4.7)†††	>0.99	5.0 (0.6–16.7)	2.0 (0.0–12.8)†††	>0.99
50–64	7.5 (5.9–9.3)	9.5 (6.4–13.5)	>0.99	7.6 (5.8–9.6)	10.5 (6.8–15.2)	>0.99	4.2 (1.0–11.3)	7.3 (1.4–20.7)†††	>0.99
≥65	12.3 (10.2–14.8)	18.5 (13.8–23.9)	0.70	12.0 (9.6–14.7)	18.6 (12.6–25.9)	>0.99	8.2 (4.5–13.5)	17.4 (10.5–26.3)	>0.99

Abbreviations: A/PI = Asian or Pacific Islander; AI/AN = American Indian or Alaska Native; CI = confidence interval; ICU = intensive care unit.

* Data are from a weighted sample of hospitalized nonpregnant adults with completed medical record abstractions and a discharge disposition. Sample sizes presented are unweighted with weighted percentages.

^† Vaccination status is not available for Iowa. Vaccination status is based on state immunization information system data. Fully vaccinated adults with a COVID-19–associated hospitalization were persons who had received the second dose of a 2-dose COVID-19 vaccine series or a single dose of a 1-dose product ≥14 days before receiving a positive SARS-CoV-2 test result associated with their hospitalization. Adults whose positive SARS-CoV-2 test date was ≥14 days after the first dose of a 2-dose series but <14 days after receipt of the second dose were considered partially vaccinated. Partially vaccinated adults, and those who received a single dose of a vaccine <14 days before the positive SARS-CoV-2 test result were not included in analyses by vaccination status but were included in rates and overall proportions that were not stratified by vaccination status. Adults with no documented receipt of any COVID-19 vaccine dose before the test date were considered unvaccinated. If the SARS-CoV-2 test date was not available, hospital admission date was used. Adults whose vaccination status had not yet been verified using the immunization information system data were considered to have missing vaccination status and were included in total proportions not stratified by vaccination status. Additional COVID-NET methods for determining vaccination status have been described previously. https://www.medrxiv.org/content/10.1101/2021.08.27.21262356v1

^§ January–June 2021 is the pre-Delta period; the Delta period (July–August 2021) is when the Delta variant was the predominant circulating variant.

^¶ Selected counties in California, Colorado, Connecticut, Georgia, Iowa, Maryland, Michigan, Minnesota, New Mexico, New York, Ohio, Oregon, Tennessee, and Utah can be found at https://www.cdc.gov/mmwr/volumes/69/wr/mm6915e3.htm.

** Total hospitalizations include data from selected counties in all 14 COVID-NET states with vaccination status, including fully vaccinated, partially vaccinated, and unvaccinated adults. As a result, the number of total hospitalizations exceeds the sum of fully vaccinated and unvaccinated adults.

^†† Proportions between the pre-Delta and Delta period were compared with chi-square tests; p-values <0.05 were considered statistically significant, adjusted for multiple comparisons using the Bonferroni correction method.

^§§ Percentages presented for demographic characteristics are weighted column percentages.

^¶¶ Black, White, AI/AN, and A/PI persons were non-Hispanic; Hispanic persons could be of any race. If Hispanic ethnicity was unknown, non-Hispanic ethnicity was assumed. Persons with multiple, unknown, or missing race accounted for 3.4% (weighted) of all cases. These persons are excluded from the proportions of race/ethnicity but are otherwise included elsewhere in the analysis.

*** Long-term care facility residents include hospitalized adults who were identified as residents of a nursing home/skilled nursing facility, rehabilitation facility, assisted living/residential care, long-term acute care hospital, group/retirement home, or other long-term care facility upon hospital admission. A free-text field for other types of residences was examined; patients with a long-term care facility-type residence were also categorized as long-term care facility residents.

^††† Relative standard errors >30%.

^§§§ Percentages presented for hospitalization outcomes and interventions are weighted percentages of each age group with that outcome or intervention in the pre-Delta or Delta period.

^¶¶¶ ICU admission status was missing in 0.9% (weighted) of hospitalizations; these hospitalizations are otherwise included elsewhere in the analysis.

**** Results with relative standard errors >30% and CI widths >20 were suppressed.

^†††† CI widths >20.

^§§§§ Invasive of mechanical ventilation status was missing in 0.9% (weighted) of hospitalizations; these hospitalizations are otherwise included elsewhere in the analysis.

^¶¶¶¶ In-hospital death status was missing in 1.2% (weighted) of hospitalizations; these hospitalizations are otherwise included elsewhere in the analysis.