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COVID-19 Variants of Concern

Variant Proportions Chart

Information about the characteristics of COVID-19 variants is continually emerging. Scientists are working to learn more about how easily they spread, whether they could cause more severe illness, and whether currently authorized vaccines will protect people against them.

The CDC categorizes variants as “Variants of Concern” (VOC) based upon the evidence of an increase in transmissibility, more severe disease, significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.

What We Know

Viruses constantly change through mutation, and new variants of a virus are expected to occur over time. Sometimes new variants emerge and disappear. Other times, new variants emerge and persist. Multiple variants of the virus that causes COVID-19 have been documented in the United States and globally during this pandemic.

The virus that causes COVID-19 is a type of coronavirus, a large family of viruses. Coronaviruses are named for the crown-like spikes on their surfaces. Scientists monitor changes in the virus, including changes to the spikes on the surface of the virus. These studies, including genetic analyses of the virus, are helping scientists understand how changes to the virus might affect how it spreads and what happens to people who are infected with it.

Multiple variants of the virus that causes COVID-19 are circulating globally:

As of December 2022, there are multiple subvariants of the Omicron variant that are under surveillance.

These variants seem to spread more easily and quickly than other variants, which may lead to more cases of COVID-19. An increase in the number of cases will put more strain on health care resources, lead to more hospitalizations, and potentially more deaths.

The bivalent COVID-19 vaccine includes a component of the original virus strain to provide broad protection against COVID-19 as well as a component of the Omicron variant to protect against the specific variant that is currently circulating widely across the United States.

Rigorous and continuous compliance with public health mitigation strategies, such as vaccination, physical distancing, use of masks, hand hygiene, and isolation and quarantine, is essential to limit the spread of the virus that causes COVID-19 and protect public health.

What It Means

Public health officials are studying these variants as they emerge to learn more to control their spread. They want to understand whether the variants:

  • Spread more easily from person-to-person
  • Cause milder or more severe disease in people
  • Are detected by currently available viral tests
  • Respond to medicines currently being used to treat people for COVID-19
  • Change the effectiveness of COVID-19 vaccines

What IDPH is Doing

IDPH, in collaboration with the CDC, is monitoring Illinois closely. IDPH laboratories are analyzing COVID-19 samples each week to monitor the spread of identified variants, characterize emerging viral variants, and expand its ability to find new SARS-CoV-2 variants.

In addition, IDPH has also partnered with the Discovery Partners Institute (DPI) which is part of the University of Illinois System to develop the Illinois Wastewater Surveillance System (IWSS) to further monitor trends of COVID-19 variants.

Last Updated: December 6, 2022

Variant Proportions Data

Week Ending Lineage Percent Lineage