Variants of COVID-19

What is a variant?

Viruses constantly change through mutations that create new strains of virus (called variants) over time. Some virus variants emerge and then disappear, while others persist or become common. Most variants do not have a meaningful impact. Public health becomes concerned about a SARS-CoV-2 variant when it affects COVID-19 transmission, severity, testing, treatment, or vaccine effectiveness.

How are variants identified?

Multiple variants of the virus that causes COVID-19 have been identified globally during the COVID-19 pandemic. Variants are determined by their genetic sequences. It's important to understand that genetic mutations of the virus that causes COVID-19, SARS-CoV-2, are expected, and that there are many strains of the virus. Public health, academic, and clinical partners are working together to determine the full genetic sequence of the virus circulating in California. The term variant of interest (VOI) is used to describe a newly emerging variant for which the medical and public health importance is not yet known. If a variant is thought to be more contagious or likely to cause greater illness or severe disease, or may impact treatment or vaccine response, then it is considered a variant of concern (VOC).

Why are we tracking variants?

Scientists and public health officials are studying variants to learn more about how 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-
    Change the effectiveness of COVID-19 vaccines  

What do we know about the variants of concern?

B.1.1.7 (Alpha) variants are associated with approximately 50% increased transmission, and likely with increased disease severity and risk of death. Appears to have minimal impact on the effectiveness of treatments with antibodies.

B.1.351 (Beta) variants are associated with approximately 50% increased transmission. May have moderately decreased response to antibody treatments.

P.1 (Gamma) variants may have moderately decreased response to some antibody treatments.

B.1.617.2 (Delta) variants are associated with increased transmission. May have moderately decreased response to antibody treatments.

Does the COVID-19 vaccine protect against variants, including the Delta variant?

Yes. However, no vaccine offers 100 percent protection. COVID-19 vaccines provide excellent protection from serious disease, hospitalization, and even death – including against the Delta variant. The Delta variant is more easily transmitted than other strains. While new research shows vaccinated people can become infected and carry high levels of the coronavirus, it’s important to remember that it’s primarily the unvaccinated who get infected and spread the virus. 

What are post-vaccine cases and how likely are they?

Post-vaccine cases (sometimes called breakthrough cases) are when a fully vaccinated person gets infected with COVID-19. As no vaccine is 100 percent effective, some post-vaccine cases are expected. Vaccinated individuals typically have far less severe symptoms and far more favorable outcomes when contracting COVID-19 than those who remain unvaccinated.

Content from the California Department of Public Health