COVID-19 Associated Hospitalizations Surveillance

Overview

As part of the CDC’s Emerging Infections Program, CEIP conducts active, laboratory and population-based surveillance for all laboratory-confirmed COVID-19 hospitalizations among residents of Alameda, Contra Costa, and San Francisco counties. For each case, CEIP generates a case report form with basic demographic, SARS-CoV-2 testing, and admission information. Data are entered into a secure local database. De-identified case report data are transmitted weekly to CDC and included with data from other COVID-NET sites.

COVID-NET Purpose

The SARS-CoV-2 (COVID-19)-Associated Hospitalization Surveillance Network (COVID-NET) is a population-based surveillance system that collects data on laboratory-confirmed COVID-19-associated hospitalizations among children and adults through a network of acute-care hospitals in 13 states participating in the Emerging Infections Program (EIP) and is part of the Respiratory Virus Hospitalization Surveillance Network (RESP-NET). The purpose is to inform clinical and public health response and to estimate the national disease burden of COVID-19. https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covid-net/purpose-methods.html

Surveillance Objectives:

Primary

  1. Estimate national COVID-19-associated hospitalization rates in all ages in a timely manner (e.g., weekly,).
  2. Estimate COVID-19-associated intensive care unit (ICU) hospitalization rates and in-hospital mortality rates in all ages.

Secondary

  1. Describe the characteristics, clinical features, and clinical course (e.g., severe illness and associated complications) of persons hospitalized with COVID-19.
  2. Estimate rates of laboratory-confirmed COVID-19 hospitalizations by vaccination status
  3. Assess risk factors for COVID-19-associated complications among hospitalized cases.

Case Finding

Case ascertainment utilizes reports from hospital laboratories, admission/discharge information, infection control practitioner logs/databases, and review of the California Department of Public Health (CDPH) reportable diseases database, California Reportable Disease Information Exchange (CalREDIE), to identify hospitalized COVID-19 cases in catchment area residents. All cases are logged into a database, and de-identified data are transmitted weekly to CDC.

Case Definition

A case is defined by laboratory confirmed SARS-CoV-2 in a person who:

  • A resident of Alameda, Contra Costa, or San Francisco counties
  • Tests positive for SARS-CoV-2 within 14 days before or during hospitalization.

Evidence of COVID-19 infection can be obtained through several laboratory tests:

  • Molecular assays, such as reverse transcription polymerase chain reaction (RT-PCR)
  • Commercially available rapid antigen detection tests

Active Surveillance

CEIP Surveillance Officers complete a standardized case report form (CRF) for a subset of cases hospitalized in the previous month, following CDC’s sampling guidance, to inform clinical and public health response. Information collected for each sampled case includes demographics, admission and discharge information and clinical course.

Geocoding and Linkage to Census Data

Case address at time of admission is geocoded for a sample of cases using standard software to determine the census tract of residence. The census tract is linked to US Census data to obtain socioeconomic indicators associated with the census tract. These data can be used to find associations between geographic location, socioeconomic indicators, and risk for hospitalization with COVID-19.

Death Ascertainment

Surveillance data are linked to state vital death data to determine whether a case-patient has died during hospitalization or within 60 days after discharge date.

Burden Estimate

The purpose of the Burden Estimation Project is to assess under-ascertainment of persons hospitalized with influenza, RSV, and COVID-19 from non-testing and under-reporting in order to adjust the number of confirmed cases reported in RESP-NET. These efforts will contribute to the seasonal multiplier model used to estimate the annual disease burden of influenza, COVID-19, and RSV cases, hospitalizations, and deaths. There are two primary objectives of the project:

  1. To determine the frequency of influenza, RSV, and SARS-CoV-2 testing and test types used to estimate multipliers to correct for the under-detection of influenza, RSV, and COVID-19-associated hospitalizations.
  2. To use multipliers to determine the annual burden of influenza-, RSV-, and COVID-19-associated hospitalizations and the burden averted through vaccination and other clinical interventions.

COVID-NET Summarized Data

COVID-19-associated hospitalization cases are reported to CDC on a weekly basis. COVID-NET data, including hospitalization rates for different age groups and data on patient characteristics, are available on COVIDView:   https://covid.cdc.gov/covid-data-tracker/#datatracker-home

Publications

Publications containing important public health findings derived from the surveillance data collected by the CEIP and the national COVID-Net sites can be found at the following link (bottom of webpage):

https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covid-net/purpose-methods.html

Contact

For questions about COVID-19 surveillance and projects, please contact:

Pam Daily Kirley, MPH
California Emerging Infections Program
RESP-NET Project Manager
respnet@ceip.us

Information and Guidance for the Public: