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August 17, 2021

COVID-19 variants and Delta explained

Madison, Wis. – The Delta variant has become the dominant strain of COVID-19 in the United States and is discussed widely as especially dangerous, but what is a variant and what makes Delta concerning to physicians and disease experts?

UW Health is breaking down how variants work, what you need to know about Delta, and the best way to protect yourself and your family.

According to the Centers for Disease Control and Prevention, viruses constantly change through mutation, causing a different version – or variant – of the virus. Sometimes these variants make the virus more severe, more deadly or more contagious.

The CDC says the Delta variant is far more contagious than previous strains of COVID-19, and could cause up to twice as many infections, meaning if one person with the original strain of COVID-19 infected two people with the virus on average, a person infected with the Delta variant could infect four people under similar circumstances.

According to the CDC, some data suggest the Delta variant might cause more severe illness than previous strains in unvaccinated individuals. Two different studies in Canada and Scotland reported patients infected with the Delta variant were more likely to be hospitalized than patients affected by the original COVID-19 strain.

As experts learn more about the Delta variant, the CDC updated its guidance, recommending people wear masks in public places indoors, even if they are fully vaccinated, because Delta can spread so fast. Breakthrough cases are rare, but there is evidence that even a vaccinated person who contracts the Delta variant can spread the virus. Plus, there are many people – such as children younger than 12 – who cannot yet get vaccinated and benefit from mask wearing.

“Cases and hospitalizations are rising at pretty alarming rates,” said Dr. Jeff Pothof, chief quality officer, UW Health. “Until we get higher vaccination rates, we are going to continue to see risk with gatherings, strains on the healthcare system, and issues with future variants.”

The authorized COVID-19 vaccines are highly effective at preventing severe disease and death, including against the Delta variant, according to Pothof. While some fully vaccinated people will become infected with a “breakthrough” infection, the vaccine still provides strong protection against serious illness and death. The best way to be protected is to get vaccinated and wear masks as recommended.