Tracking COVID-19 in the United States With Surveillance of Aggregate Cases and Deaths

Abstract

Early during the COVID-19 pandemic, the Centers for Disease Control and Prevention (CDC) leveraged an existing surveillance system infrastructure to monitor COVID-19 cases and deaths in the United States. Given the time needed to report individual-level (also called line-level) COVID-19 case and death data containing detailed information from individual case reports, CDC designed and implemented a new aggregate case surveillance system to inform emergency response decisions more efficiently, with timelier indicators of emerging areas of concern. We describe the processes implemented by CDC to operationalize this novel, multifaceted aggregate surveillance system for collecting COVID-19 case and death data to track the spread and impact of the SARS-CoV-2 virus at national, state, and county levels. We also review the processes established to acquire, process, and validate the aggregate number of cases and deaths due to COVID-19 in the United States at the county and jurisdiction levels during the pandemic. These processes include time-saving tools and strategies implemented to collect and validate authoritative COVID-19 case and death data from jurisdictions, such as web scraping to automate data collection and algorithms to identify and correct data anomalies. This topical review highlights the need to prepare for future emergencies, such as novel disease outbreaks, by having an event-agnostic aggregate surveillance system infrastructure in place to supplement line-level case reporting for near–real-time situational awareness and timely data.

Representativeness of a national, probability-based panel survey of COVID-19 isolation practices—United States, 2020–2022

“…COVID-19 case-based reporting includes individual demographic characteristics such as age, sex, and race/ ethnicity (1). CDC released weekly aggregated case-based COVID-19 surveillance and mortality data beginning in March 2020 (12). We used a probability-based panel survey of a nationally representative sample to understand the actions of people who self-reported positive SARS-CoV-2 test results (7).…”

Correlations and Timeliness of COVID-19 Surveillance Data Sources and Indicators ― United States, October 1, 2020–March 22, 2023

“…Authorizations to collect certain categories of public health data will expire on May 11, 2023 ( 1 ), including national data on the percentage of positive SARS-CoV-2 test results from CELR ( 2 ); national reporting of aggregate case and death counts, which CDC compiles from official public health jurisdiction sources, will also be discontinued ( 3 ). CDC will transition to using provisional mortality data from NVSS as the primary data source on COVID-19 deaths ( 4 ) and to using SARS-CoV-2 test positivity data from NREVSS, an established sentinel network of more than 450 clinical, public health, and commercial laboratories ( 5 ).…”