This post originally appeared on the Health Feed blog.

Different versions, or variants, of the virus that causes COVID-19 (SARS-CoV-2) are emerging around the world. Although it sounds alarming, viruses always change via mutation. As scientists work to learn more about these variants and how they may impact the United States, Stephen Goldstein, PhD, a postdoctoral research associate in the Department of Human Genetics at University of Utah, shares information about what is currently known.

How variants from viruses emerge

All viruses mutate.

Every time a virus replicates, errors (mutations) occur in its genetic material. This is normal—and it’s how variants arise. Usually, the changes either have no impact or are harmful to the virus. But once in a while, there are changes that give the virus an advantage. This is what has happened with the SARS-CoV-2 variants of concern.

Scientists are studying these variants closely to determine whether they spread more easily. They are also investigating how effective today’s COVID-19 vaccines are against the variants and whether people who have already had COVID-19 could become infected with the variants. So far, studies suggest that current vaccines work on these variants.

Types of COVID-19 variants

Several variants of the SARS-CoV-2  virus have been identified around the world. The Centers for Disease Control and Prevention (CDC) have identified four variants of concern in the United States. According to the CDC, these variants seem to spread more easily and quickly than other variants. Each variant arose independently and all have unique mutations as well as mutations in common.

United Kingdom (Alpha) variant

• Emerged with a large number of mutations in the United Kingdom in September 2020 and was detected in the United States in December 2020.
• The variant is ~50% more transmissible than the original SARS-CoV-2 virus and is associated with an increased risk of hospitalization and death.
• New cases due to this variant are declining in the United States.

South Africa (Beta) variant

• Emerged independently in South Africa in December 2020 and was detected in the United States in January 2021.
• Spreads more quickly than non-variant SARS-CoV-2
• Most vaccines exhibit modest reduction in efficacy against this variant
• There is no evidence that it causes more severe illness or increases risk of death.
• Very few cases of the variant have been found in the U.S.

Brazil (Gamma) variant

• First emerged in Brazil in November 2020 and was detected in the United States at the end of January 2021.
• It shares some critical mutations with Beta.
• Is more susceptible to antibodies than Beta.
• Spreads more quickly than the original, non-variant SARS-CoV-2.
• Remains rare in the United States, though cases have increased steadily.

India (Delta) variant

• First identified in December 2020 in India during a surge responsible for more than 30 million infections and 400,000 deaths.
• The variant was first detected in the United States in March 2021 and is now recognized as the dominant variant in the U.S., as well as in the U.K.
• It’s believed to be 50% more transmissible than the Alpha variant (which was 50% more transmissible than the original, non-variant SARS-CoV-2).
• Although some reports claim it causes more severe disease, more research needs to be done to verify this effect.
• Due the Delta variant, COVID-19 cases and hospitalizations have risen in the U.S.
• One dose of a two-dose vaccine is only partially effective against this variant.
• Full vaccination (achieved when it has been at least two weeks after the final dose of vaccine) remains highly effective against both symptomatic infection and severe disease/hospitalization.
• Spread of this variant may overwhelm health care systems in regions where vaccination rates are low.

How variants are discovered

Variants are discovered by taking a swab from an infected patient, extracting genetic material from virus that is in the sample, and using sequencing equipment to read the genetic code. This is how testing laboratories in the U.K. found that country’s Alpha variant. Goldstein describes their viral genome sequencing program as the best in the world. Programs like this one also monitor the spread of variants within the population.

Potential impact on health care systems

When a variant is more transmissible, it could impact more people by rapidly increasing the number of coronavirus cases and hospitalizations. This could overwhelm health care systems and ultimately impact the quality of care.

Because of this, “a virus that’s more contagious but does not cause more severe illness is worse than a virus that’s not more contagious but does cause more severe illness,” Goldstein says.

How to protect yourself against COVID-19 variants

The best way to avoid getting infected with the new variants is to get vaccinated. While scientists continue to study vaccine efficacy on these variants, COVID-19 vaccines are considered to be the best method to protect yourself from preventing severe illness, hospitalization, and death from COVID-19.

With more transmissible variants emerging, it is important for unvaccinated individuals to continue practicing interventions. This means following COVID-19 safety protocols such as wearing a face mask in public places, physical distancing, frequently washing your hands, and staying home when sick. Fully vaccinated individuals should also consider following the same interventions when in crowded, indoor spaces in regions of the country that are known to have high rates of COVID-19.