COVID-19-associated hospitalizations among vaccinated and unvaccinated adults >=18 years - COVID-NET, 13 states, January 1 - July 24, 2021

BackgroundAs of August 21, 2021, >60% of the U.S. population aged [≥]18 years were fully vaccinated with vaccines highly effective in preventing hospitalization due to Coronavirus Disease-2019 (COVID-19). Infection despite full vaccination (vaccine breakthrough) has been reported, but characteristics of those with vaccine breakthrough resulting in hospitalization and relative rates of hospitalization in unvaccinated and vaccinated persons are not well described, including during late June and July 2021 when the highly transmissible Delta variant predominated. MethodsFrom January 1-June 30, 2021, cases defined as adults aged [≥]18 years with laboratory-confirmed Severe Acute Respiratory Coronavirus-2 (SARS-CoV-2) infection were identified from >250 acute care hospitals in the population-based COVID-19-Associated Hospitalization Surveillance Network (COVID-NET). Through chart review for sampled cases, we examine characteristics associated with vaccination breakthrough. From January 24-July 24, 2021, state immunization information system data linked to both >37,000 cases representative cases and the defined surveillance catchment area population were used to compare weekly hospitalization rates in vaccinated and unvaccinated individuals. Unweighted case counts and weighted percentages are presented. ResultsFrom January 1 - June 30, 2021, fully vaccinated cases increased from 1 (0.01%) to 321 (16.1%) per month. Among 4,732 sampled cases, fully vaccinated persons admitted with COVID-19 were older compared with unvaccinated persons (median age 73 years [Interquartile Range (IQR) 65-80] v. 59 years [IQR 48-70]; p<0.001), more likely to have 3 or more underlying medical conditions (201 (70.8%) v. 2,305 (56.1%), respectively; p<0.001) and be residents of long-term care facilities [37 (14.5%) v. 146 (5.5%), respectively; p<0.001]. From January 24 - July 24, 2021, cumulative hospitalization rates were 17 times higher in unvaccinated persons compared with vaccinated persons (423 cases per 100,000 population v. 26 per 100,000 population, respectively); rate ratios were 23, 22 and 13 for those aged 18-49, 50-64, and [≥]65 years respectively. For June 27 - July 24, hospitalization rates were [≥]10 times higher in unvaccinated persons compared with vaccinated persons for all age groups across all weeks. ConclusionPopulation-based hospitalization rates show that unvaccinated adults aged [≥]18 years are 17 times more likely to be hospitalized compared with vaccinated adults. Rates are far higher in unvaccinated persons in all adult age groups, including during a period when the Delta variant was the predominant strain of the SARS-CoV-2 virus. Vaccines continue to play a critical role in preventing serious COVID-19 illness and remain highly effective in preventing COVID-19 hospitalizations.

Clinical Trends Among U.S. Adults Hospitalized with COVID-19, March-December 2020

BackgroundThe COVID-19 pandemic has caused substantial morbidity and mortality. ObjectivesTo describe monthly demographic and clinical trends among adults hospitalized with COVID-19. DesignPooled cross-sectional. Setting99 counties within 14 states participating in the Coronavirus Disease 2019-Associated Hospitalization Surveillance Network (COVID-NET). PatientsU.S. adults (aged [≥]18 years) hospitalized with laboratory-confirmed COVID-19 during March 1-December 31, 2020. MeasurementsMonthly trends in weighted percentages of interventions and outcomes including length of stay (LOS), intensive care unit admissions (ICU), invasive mechanical ventilation (IMV), vasopressor use and in-hospital death (death). Monthly hospitalization, ICU and death rates per 100,000 population. ResultsAmong 116,743 hospitalized adults, median age was 62 years. Among 18,508 sampled adults, median LOS decreased from 6.4 (March) to 4.6 days (December). Remdesivir and systemic corticosteroid use increased from 1.7% and 18.9% (March) to 53.8% and 74.2% (December), respectively. Frequency of ICU decreased from 37.8% (March) to 20.5% (December). IMV (27.8% to 8.7%), vasopressors (22.7% to 8.8%) and deaths (13.9% to 8.7%) decreased from March to October; however, percentages of these interventions and outcomes remained stable or increased in November and December. Percentage of deaths significantly decreased over time for non-Hispanic White patients (p-value <0.01) but not non-Hispanic Black or Hispanic patients. Rates of hospitalization (105.3 per 100,000), ICU (20.2) and death (11.7) were highest during December. LimitationsCOVID-NET covers approximately 10% of the U.S. population; findings may not be generalizable to the entire country. ConclusionsAfter initial improvement during April-October 2020, trends in interventions and outcomes worsened during November-December, corresponding with the 3rd peak of the U.S. pandemic. These data provide a longitudinal assessment of trends in COVID-19-associated outcomes prior to widespread COVID-19 vaccine implementation.

Risk Factors for COVID-19-associated hospitalization: COVID-19-Associated Hospitalization Surveillance Network and Behavioral Risk Factor Surveillance System

BackgroundIdentification of risk factors for COVID-19-associated hospitalization is needed to guide prevention and clinical care. ObjectiveTo examine if age, sex, race/ethnicity, and underlying medical conditions is independently associated with COVID-19-associated hospitalizations. DesignCross-sectional. Setting70 counties within 12 states participating in the Coronavirus Disease 2019-Associated Hospitalization Surveillance Network (COVID-NET) and a population-based sample of non-hospitalized adults residing in the COVID-NET catchment area from the Behavioral Risk Factor Surveillance System. ParticipantsU.S. community-dwelling adults ([≥]18 years) with laboratory-confirmed COVID-19-associated hospitalizations, March 1- June 23, 2020. MeasurementsAdjusted rate ratios (aRR) of hospitalization by age, sex, race/ethnicity and underlying medical conditions (hypertension, coronary artery disease, history of stroke, diabetes, obesity [BMI [≥]30 kg/m2], severe obesity [BMI[≥]40 kg/m2], chronic kidney disease, asthma, and chronic obstructive pulmonary disease). ResultsOur sample included 5,416 adults with COVID-19-associated hospitalizations. Adults with (versus without) severe obesity (aRR:4.4; 95%CI: 3.4, 5.7), chronic kidney disease (aRR:4.0; 95%CI: 3.0, 5.2), diabetes (aRR:3.2; 95%CI: 2.5, 4.1), obesity (aRR:2.9; 95%CI: 2.3, 3.5), hypertension (aRR:2.8; 95%CI: 2.3, 3.4), and asthma (aRR:1.4; 95%CI: 1.1, 1.7) had higher rates of hospitalization, after adjusting for age, sex, and race/ethnicity. In models adjusting for the presence of an individual underlying medical condition, higher hospitalization rates were observed for adults [≥]65 years, 45-64 years (versus 18-44 years), males (versus females), and non-Hispanic black and other race/ethnicities (versus non-Hispanic whites). LimitationsInterim analysis limited to hospitalizations with underlying medical condition data. ConclusionOur findings elucidate groups with higher hospitalization risk that may benefit from targeted preventive and therapeutic interventions.