COVID-19 Cases and Hospitalizations by COVID-19 Vaccination Status and Previous COVID-19 Diagnosis — California and New York, May–November 2021

León, Tomás Munilla; Dorabawila, Vajeera; Nelson, Lauren; Lutterloh, Emily; Bauer, Ursula E.; Backenson, Bryon; Bassett, Mary T.; Henry, H. Balfour; Bregman, Brooke; Midgley, Claire M; Myers, Jennifer F.; Plumb, Ian D.; Reese, Heather; Zhao, Rui; Briggs-Hagen, Melissa; Hoefer, Dina; Watt, James; Silk, Benjamin J.; Jain, Seema; Rosenberg, Eli S.

doi:10.15585/mmwr.mm7104e1

Cited by 130 publications

(148 citation statements)

References 8 publications

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“…These findings align with those from recent studies, indicating that COVID-19 vaccination protects against severe COVID-19 caused by SARS-CoV-2 variants, including Omicron (7,8). *** Efforts to promote COVID-19 vaccination and boosters are critical to preventing COVID-19-associated hospitalizations and severe outcomes.…”

Section: Discussionsupporting

confidence: 87%

SARS-CoV-2 Infection and Hospitalization Among Adults Aged ≥18 Years, by Vaccination Status, Before and During SARS-CoV-2 B.1.1.529 (Omicron) Variant Predominance — Los Angeles County, California, November 7, 2021–January 8, 2022

Danza

Koo

Haddix

et al. 2022

MMWR Morb. Mortal. Wkly. Rep.

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On February 1, 2022, this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).COVID-19 vaccines are effective at preventing infection with SARS-CoV-2, the virus that causes COVID-19, as well as severe COVID-19-associated outcomes in real-world conditions (1,2). The risks for SARS-CoV-2 infection and COVID-19-associated hospitalization are lower among fully vaccinated than among unvaccinated persons; this reduction is even more pronounced among those who have received additional or booster doses (boosters) (3,4). Although the B.1.1.529 (Omicron) variant spreads more rapidly than did earlier SARS-CoV-2 variants, recent studies suggest that disease severity is lower for Omicron compared with that associated with the B.1.617.2 (Delta) variant; but the high volume of infections is straining the health care system more than did previous waves (5).* , † The Los Angeles County (LAC) Department of Public Health (LACDPH) used COVID-19 surveillance and California Immunization Registry 2 (CAIR2) data to describe age-adjusted 14-day cumulative incidence and hospitalization rates during November 7, 2021-January 8, 2022, by COVID-19 vaccination status and variant predominance. For the 14-day period ending December 11, 2021, the last week of Delta predominance, the incidence and hospitalization rates among unvaccinated persons were 12.3 and 83.0 times, respectively, those of fully vaccinated persons with a booster and 3.8 and 12.9 times, respectively, those of fully vaccinated persons without a booster. These rate ratios were lower during Omicron predominance (week ending January 8, 2022), with unvaccinated persons having infection and hospitalization rates 3.6 and 23.0 times, respectively, those of fully vaccinated persons with a booster and 2.0 and 5.3 times, respectively, those of fully vaccinated persons without a booster. In addition, during the entire analytic period, admission to intensive care units (ICUs), intubation for mechanical ventilation, and death were more likely to occur among unvaccinated persons than among fully vaccinated persons without or with a booster (p<0.001). Incidence and hospitalization rates were consistently highest for unvaccinated persons and lowest for fully vaccinated persons with a booster. Being up to date with COVID-19 vaccination is *

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Section: Discussionsupporting

confidence: 87%

SARS-CoV-2 Infection and Hospitalization Among Adults Aged ≥18 Years, by Vaccination Status, Before and During SARS-CoV-2 B.1.1.529 (Omicron) Variant Predominance — Los Angeles County, California, November 7, 2021–January 8, 2022

Danza

Koo

Haddix

et al. 2022

MMWR Morb. Mortal. Wkly. Rep.

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“…Children's susceptibility to the Omicron variant and the impact of changes in exposure on severity risk require additional study. Among adults aged ≥18 years, all in-hospital severity indicators assessed were lower during the Omicron period, which might be related to increased population immunity against SARS-CoV-2 because of higher vaccination coverage and booster rates and previous infection providing protection (3,4,7,9). Receipt of a third mRNA vaccine dose was found to be highly effective at preventing urgent care encounters, ED visits, and hospital admissions during both Delta and Omicron periods (9).…”

Section: Discussionmentioning

confidence: 98%

Trends in Disease Severity and Health Care Utilization During the Early Omicron Variant Period Compared with Previous SARS-CoV-2 High Transmission Periods — United States, December 2020–January 2022

Iuliano¹,

Brunkard²,

Boehmer³

et al. 2022

MMWR Morb. Mortal. Wkly. Rep.

350

339

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On January 25, 2022 this report was posted as an MMWR Early Release on the MMWR website (https://www.cdc.gov/mmwr).The B.1.1.529 (Omicron) variant of SARS-CoV-2, the virus that causes COVID-19, was first clinically identified in the United States on December 1, 2021, and spread rapidly. By late December, it became the predominant strain, and by January 15, 2022, it represented 99.5% of sequenced specimens in the United States* (1). The Omicron variant has been shown to be more transmissible and less virulent than previously circulating variants (2,3). To better understand the severity of disease and health care utilization associated with the emergence of the Omicron variant in the United States, CDC examined data from three surveillance systems and a large health care database to assess multiple indicators across three high-COVID-19 transmission periods:

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“…Unvaccinated patients with history of prior COVID-19 were grouped with vaccinated patients for stratified analyses based on reports showing similar protective effects. 20 Severe COVID-19 was defined as respiratory support with high flow nasal cannula, noninvasive positive pressure ventilation, or mechanical ventilation. 21 The primary outcome was severe disease or death within 14 days of hospital presentation, chosen because severe COVID-19 onset occurs within this timeframe for nearly all patients who develop severe disease.…”

Section: Cohort Composition and Outcome Determinationmentioning

confidence: 99%

Impact of SARS-CoV-2 variants on inpatient clinical outcome

Robinson

Morris

Betz

et al. 2022

Preprint

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BackgroundPrior observation has shown differences in COVID-19 hospitalization rates between SARS-CoV-2 variants, but limited information describes differences in hospitalization outcomes.MethodsPatients admitted to 5 hospitals with COVID-19 were included if they had hypoxia, tachypnea, tachycardia, or fever, and data to describe SARS-CoV-2 variant, either from whole genome sequencing, or inference when local surveillance showed ≥95% dominance of a single variant. The average effect of SARS-CoV-2 variant on 14-day risk of severe disease, defined by need for advanced respiratory support, or death was evaluated using models weighted on propensity scores derived from baseline clinical features.ResultsSevere disease or death within 14 days occurred for 950 of 3,365 (28%) unvaccinated patients and 178 of 808 (22%) patients with history of vaccination or prior COVID-19. Among unvaccinated patients, the relative risk of 14-day severe disease or death for Delta variant compared to ancestral lineages was 1.34 (95% confidence interval [CI] 1.13-1.55). Compared to Delta variant, this risk for Omicron patients was 0.78 (95% CI 0.62-0.97) and compared to ancestral lineages was 1.04 (95% CI 0.84-1.24). Among Omicron and Delta infections, patients with history of vaccination or prior COVID-19 had one-half the 14-day risk of severe disease or death (adjusted hazard ratio 0.46, IQR 0.34-0.62) but no significant outcome difference between Delta and Omicron infections.ConclusionsAlthough the risk of severe disease or death for unvaccinated patients with Omicron was lower than Delta, it was similar to ancestral lineages. Severe outcomes were less common in vaccinated patients, but there was no difference between Delta and Omicron infections.

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COVID-19 Cases and Hospitalizations by COVID-19 Vaccination Status and Previous COVID-19 Diagnosis — California and New York, May–November 2021

Abstract: Vaccinated, no previous COVID-19 diagnosis Unvaccinated, previous COVID-19 diagnosis Vaccinated, previous COVID-19 diagnosis Unvaccinated, previous COVID-19 diagnosis Vaccinated, previous COVID-19 diagnosis Cases, California May 30-Jun 5 20.

Cited by 130 publications

References 8 publications

SARS-CoV-2 Infection and Hospitalization Among Adults Aged ≥18 Years, by Vaccination Status, Before and During SARS-CoV-2 B.1.1.529 (Omicron) Variant Predominance — Los Angeles County, California, November 7, 2021–January 8, 2022

SARS-CoV-2 Infection and Hospitalization Among Adults Aged ≥18 Years, by Vaccination Status, Before and During SARS-CoV-2 B.1.1.529 (Omicron) Variant Predominance — Los Angeles County, California, November 7, 2021–January 8, 2022

Trends in Disease Severity and Health Care Utilization During the Early Omicron Variant Period Compared with Previous SARS-CoV-2 High Transmission Periods — United States, December 2020–January 2022

Impact of SARS-CoV-2 variants on inpatient clinical outcome

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