What is the Delta variant?

Medically reviewed on November 2, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Vaccine distribution has grown — though there are still plenty of populations who have trouble accessing vaccines — and there is almost the smallest dot of light at the end of the tunnel. One of the biggest blockages to seeing the end of the coronavirus pandemic is the growth and spread of the Delta variant. Learn more about this variant below and how it influences vaccine effectiveness.

What is the Delta variant?

Viruses naturally go through mutations. COVID-19 is no exception, and it has gone through various iterations, but none of them have been as prominent as the Delta variant. This new variant is quite similar to previous variants. However, this mutation is causing a higher level of COVID breakthrough cases. It was initially discovered in India in December 2020, and it has since become the predominant strain of the COVID-19 virus. By the end of July 2021, the Delta variant was responsible for more than 80 percent of new COVID-19 cases in the United States [1].

The main problem with this strain is how transmissible it is. It is twice as contagious as the original strain of COVID-19, but vaccination still offers significant protection against the Delta variant.

Delta variant symptoms: are they different?

Currently, differences in symptoms between the Delta variant and other strains of the SARS-CoV-2 virus are not well understood. Most cases and research show that the COVID-19 symptoms of Delta are similar to those of the original strain, including a persistent cough, sore throat, headache, and fever [1].

Some research suggests some slight differences. Coughing and loss of smell are not as common. Some people with Delta experience a runny nose, which is not common with the initial strain of SARS-CoV-2. However, each case is different and will depend on the individual [2].

What you can do

Get vaccinated! Studies show that full vaccination is still about 88 percent effective at preventing symptomatic disease caused by the Delta strain, and 96% effective at preventing hospitalizations. While breakthrough infections with the Delta variant are possible after vaccination, rates are very low, impacting an estimated 0.01 to 0.29 percent of fully vaccinated individuals in the U.S.

Vaccines are widely effective at both preventing infections and reducing the severity of disease. So if you do get a breakthrough infection with the Delta variant after getting vaccinated, your symptoms are likely to be milder and to last for fewer days.

To reduce the risks to yourself and others, public health groups are still recommending that even vaccinated people wear a mask indoors, especially in areas with high rates of community spread. Anyone who has been exposed to a person with COVID-19, or who is developing symptoms of COVID-19, should also be tested.

Experiencing COVID-19 symptoms and looking for relief? Get COVID-19 treatment online via Everlywell's Virtual Care offering.

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1. 5 Things To Know About the Delta Variant. COVID-19 Community Resources. URL. Accessed November 2, 2021.

2. SARS-CoV-2 Variant Classifications and Definitions. Centers for Disease Control and Prevention. URL. Accessed November 2, 2021.

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