- The Delta variant is the predominant strain in Wisconsin.
- The Delta variant is more than two times as infectious, causing it to spread more rapidly and cause more infections.
- The available COVID-19 vaccines are highly effective at preventing severe illness, hospitalization, and death.
- The longer a virus sticks around, the more opportunity it has to mutate into potentially more infectious and deadly variants.
- It is critical to get vaccinated and wear a mask in public, indoor settings to reduce the spread of the Delta variant and prevent the virus from mutating further.
What are SARS-CoV-2 variants and how do they occur?
A variant is a new strain of the SARS-CoV-2 virus, the virus that causes COVID-19. Variants occur through mutations, which are changes in the genetic code of a virus. Variants have specific gene mutations that make them unique and different from the original virus. Viruses, including SARS-CoV-2, naturally change or mutate over time and the new variants are expected to occur.
Public health surveillance
Variants are identified through a process called whole genome sequencing. Whole genome sequencing takes a sample of the virus from a positive SARS-CoV-2 test specimen and reads its genetic code. Genomic sequencing allows scientists to identify how virus samples from different people might have different genetic characteristics. This way, they can look out for new variants of the virus and understanding changes in the characteristics of the virus, like how easily it spreads from person-to-person.
DHS, the Wisconsin State Laboratory of Hygiene, and other laboratory partners regularly perform whole genome sequencing on a portion of positive tests. DHS has also requested that clinicians identify cases that may be good candidates for genome sequencing, such as individuals who have traveled internationally or individuals who may have tested positive after being fully vaccinated.
We sequence SARS-CoV-2 genomes in Wisconsin to understand which strains are present and how common the new strains are in our communities, not to have a real-time number of cases that are tied to each strain.
The Centers for Disease Control and Prevention (CDC) classifies variants into three categories:
- variants of interest,
- variants of concern, and
- variants of high consequence.
A variant's classification is based on its attributes, including:
- how easily it spreads,
- how sick it makes people, and
- whether COVID-19 treatments and vaccines can prevent it.
The classification of a particular variant might change based on new research. Learn more about SARS-CoV-2 variant classifications on the CDC's website.
About variants of concern tracked in Wisconsin
Delta Variant (B.1.617.2, AY.1, AY.2,...AY.12)
- The Delta variant, B.1.617.2, was first discovered in India in samples in October 2020.
- The Delta variant continues to change into new sub-lineages. Sub-lineages are newer versions of the same variant. These sub-lineages differ based on mutations in the spike protein, but they still share a lot of the mutations as the original Delta variant strain, B.1.617.2.
- Delta variant sub-lineages are classified as AY.1, AY.2, AY.3, AY.4, AY.5, AY.6, AY.7, AY.8, AY.9, AY.10, AY.11, and AY.12
- Studies show that the Delta variant is more than 2X as infectious, causing it to spread more rapidly and cause more infections than the original strain of SARS-CoV-2 and previous variants.
- Data suggests that the Delta variant might cause more severe illness, especially in unvaccinated people, than the original strain of SARS-CoV-2 and previous variants.
- Therapeutics, such as monoclonal antibody treatments, may be less effective on the Delta variant cases because of its unique mutations.
- Available evidence shows that the current COVID-19 vaccines are highly effective against severe illness, hospitalization, and death from the Delta variant. However, data suggests that there is lower effectiveness against confirmed infection and symptomatic disease caused by the Delta variant.
Alpha Variant (B.1.1.7)
- Variant B.1.1.7, the Alpha variant, was first discovered in England in November of 2020. The variant was first reported in the United States in December 2020 and was first identified in Wisconsin in January 2021.
- Researchers shows that this strain spreads more rapidly and easily than the original strain of SARS-CoV-2. The Alpha variant may also be associated with an increased risk of hospitalizations and death.
Beta Variant (B.1.351)
- Variant B.1.351, the Beta variant, was first discovered in South Africa in samples dating back to October 2020.
- Researchers have found that this strain also spreads more rapidly and easily than the original SARS-CoV-2 virus. It is not yet known if this variant has any impact on disease severity.
- There is some evidence that this variant may affect how vaccine induced antibodies respond to this virus.
Gamma Variant (P.1)
- Variant P.1, the Gamma variant, was first discovered in four travelers from Brazil who were tested at an airport near Tokyo, Japan in early January 2021.
- Therapeutics, such as monoclonal antibody treatments, may be less effective on the Gamma variant cases because of its unique mutations. Additionally, there is some evidence that this variant may affect how antibodies produced by natural infection or COVID-19 vaccine induced antibodies respond to this virus.
Vaccines reduce a virus's ability to mutate - get vaccinated!
All viruses mutate, or change, over time. Mutation can happen very slowly or more quickly. The longer a virus sticks around, the more time it has to change. When a virus changes, it is called a variant.
Many variants are no more harmful than the original virus, however, some can be more infectious or deadly. When our bodies are faced with a new variant, our immune responses built from vaccination or a previous infection may be able to fight it off.
Vaccines reduce a virus's ability to infect people. Vaccines still provide protection against current variants since many of the characteristics of the virus remain the same. The sooner people get vaccinated against COVID-19, the less opportunity we give the virus to keep mutating.
Access data on SARS-CoV-2 sequencing and variants in Wisconsin.