Coronavirus Disease 2019 (COVID-19)
2025 Case Definition

Background

In December 2019, an investigation into a cluster of pneumonia cases in Wuhan, China identified a novel coronavirus, SARS-CoV-2, which is the cause of the COVID-19. Early in the pandemic, U.S. case-based surveillance played a critical role in tracking infections, supporting rapid investigations, understanding the virus in a largely susceptible population, and aiding containment efforts like contact tracing.

As the pandemic evolved and vaccination rates increased, the utility of universal case investigation and individual case reporting diminished. By January 2022, public health organizations recognized the need for an adjusted approach, focusing on broader surveillance trends rather than individual case-based reporting. The COVID-19 Public Health Emergency (PHE) declaration officially ended in May 2023, signaling a shift in the federal response to the pandemic. This conclusion of the PHE further established the need for changes in COVID-19 surveillance and case reporting practices, which were no longer crucial in managing the COVID-19 pandemic.

In 2025, SARS-CoV-2 infection was officially removed from the list of nationally notifiable diseases. This change reflected the ongoing transition from public health emergency response to routine public health management, as the virus became endemic. With this shift, federal resources are focused towards monitoring emerging variants, severe cases, and long-term COVID-19 complications. This series of adjustments reflects the public health system’s shift toward long-term, sustainable management of COVID-19, with an emphasis on monitoring trends and emerging issues rather than focusing on individual case investigation.

To support ongoing surveillance at the state and local levels, however, the standardized case definition for COVID-19 was updated in 2025. These updates included simplified laboratory criteria for reporting COVID-19 cases, which helped align with current detection technologies, including molecular assays that do not rely on amplification. The revised criteria make case reporting more adaptable to the available diagnostic tools, allowing local jurisdictions to tailor their surveillance efforts to meet specific needs while ensuring consistency in data collection and reporting.

Laboratory Criteria

Confirmatory Laboratory Evidence:

• Detection of SARS-CoV-2 nucleic acid in a clinical or post-mortem specimen using a diagnostic molecular test (e.g., NAAT) performed by a CLIA-certified provider,*
  OR
• Detection of SARS-CoV-2 RNA in a clinical or post-mortem specimen by genomic sequencing,**
  OR
• Detection of SARS-CoV-2 specific antigen by diagnostic immunocytochemistry staining performed by a CLIA-certified provider.*

Presumptive Evidence:

• Detection of SARS-CoV-2 specific antigen in a clinical or post-mortem specimen using a diagnostic test performed by a CLIA-certified provider.*

Supportive Laboratory Evidence:

• Detection of SARS-CoV-2 nucleic acid or specific antigen using a test performed without CLIA oversight.^

Note: The categorical labels used here to stratify laboratory evidence are intended to support the standardization of case classifications for public health surveillance. The categorical labels should not be used to interpret the utility or validity of any laboratory test methodology.

* Includes those tests performed under a CLIA certificate of waiver.

** Some genomic sequencing tests that have been authorized for emergency use by the FDA do not require an initial NAAT result to be generated. Genomic sequencing results may be all the public health agency receives.

^ Includes at-home tests.

Criteria to Distinguish a New Case from an Existing Case

The following should be enumerated as a new case:

• Person was most recently enumerated as a confirmed or probable case with onset date (if available) or first positive specimen collection date for that classification >90 days prior,^‡
  OR
• SARS-CoV-2 sequencing results from the new positive specimen and a positive specimen from the most recent previous case in the same individual demonstrate a different lineage,
  OR
• Person was previously reported but not enumerated as a confirmed or probable case (i.e., suspect),^‡‡ but now meets the criteria for a confirmed or probable case.

‡ Some individuals, e.g., severely immunocompromised persons, can shed SARS-CoV-2, as detected by molecular amplification tests, >90 days after infection. For severely immunocompromised individuals, clinical judgment should be used to determine if a repeat positive test is likely to result from long-term shedding and, therefore, not be enumerated as a new case. Severe immunocompromise conditions include chemotherapy for cancer, untreated HIV infection with CD4 T lymphocyte count <200, combined primary immunodeficiency disorder, and receipt of prednisone >20mg/day for more than 14 days.

‡‡ Repeat suspect cases should not be enumerated.

Suspect

• Meets supportive laboratory evidence, OR
• Meets vital records criteria* AND no laboratory evidence for SARS-CoV-2 infection.

* A death certificate that lists COVID-19 disease or SARS-CoV-2 or an equivalent term¹ as an underlying cause of death or a significant condition contributing to death.

Probable

• Meets presumptive laboratory evidence.

Confirmed

• Meets confirmatory laboratory evidence.

• Coronavirus Disease 2019 (COVID-19) | 2023 Case Definition
• Coronavirus Disease 2019 (COVID-19) | 2021 Case Definition
• Coronavirus Disease 2019 (COVID-19) | 2020 Interim Case Definition, Approved August 5, 2020
• Coronavirus Disease 2019 (COVID-19) | 2020 Interim Case Definition, Approved April 5, 2020