A Quick Guide to Understanding COVID-19 Variants

How variants emerge and why vaccines are still the best way to protect yourself against COVID-19.

Vaccines prevent the spread of the coronavirus that causes COVID-19, which can help prevent further variants from emerging.

One of the key terms to understand during the COVID-19 pandemic is variant. A variant refers to a virus that has undergone one or more genetic changes.

Some examples of variants that have emerged during the COVID-19 pandemic include the Alpha, Beta, Delta, and Omicron variants, as well as their respective subvariants—such as BA.5 and BA.4, which are both variants of Omicron.

Here, we take a closer look at how variants occur and what they mean for someone who is trying to stay safe and healthy as the pandemic continues.

How variants occur

Viruses are said to exist in a gray area between living and nonliving. Like living organisms, viruses contain genetic material, and reproduce by passing on this genetic material. However, viruses do not possess any of the biologic machinery needed for reproduction, and they can only reproduce by infecting living cells.

During a viral infection, a virus inserts itself into cells, and uses those cells to create copies of itself. It’s common for mutations to occur during this process. This is one way that variants can occur. There are also recombinant variants, which occur when two variants of the same virus combine their genetic material, resulting in a new variant. This process is called recombination.

While it’s common for viruses to undergo changes, it’s rare for these changes to significantly alter how a virus functions. It’s estimated that a person has between 1 billion and 100 billion virions (a virion is a complete virus particle) in their body during a peak covid infection. The coronavirus that causes COVID-19 has infected hundreds of millions of people worldwide. Out of all this, only a small number of notable variants have emerged.

The Centers for Disease Control and Prevention (CDC) and The World Health Organization (WHO) continue to monitor for new variants. However, the emergence of new variants is nearly impossible to predict.

Why variants matter

Mutations and recombination can affect how a virus functions. Some variants spread through a population more easily than others. Some variants cause more severe symptoms and others more mild symptoms. Some variants are more capable of causing breakthrough infections in people who are vaccinated or causing reinfections in people who have had a previous infection.

Variants and vaccines

Getting vaccinated against COVID-19 is still the best thing you can do to reduce your risk of serious outcomes from COVID-19—outcomes like severe illness, hospitalization, and death. Staying up to date means receiving all doses of an initial vaccination as well as receiving all boosters, if boosters are required.

There are already multiple vaccines available, including mRNA vaccines (which are the first mRNA vaccines available, though the technology has been around for decades) as well as a protein-subunit vaccine (which utilizes a vaccine technology that has been in use for 30 years). Vaccine makers are also updating these vaccines to better target Omicron.

If you have questions about your risk of COVID, how existing health conditions or your overall health might influence your risk of severe illness from COVID-19, or what vaccines and boosters are right for you, talk to your healthcare provider.

Vaccines also prevent the spread of the coronavirus that causes COVID-19, which can help prevent further variants from emerging.

Article sources open article sources

Centers for Disease Control and Prevention. Variants of the Virus.
Kathy Katella. Omicron, Delta, Alpha, and More: What To Know About the Coronavirus Variants. July 5, 2022.
Centers for Disease Control and Prevention. SARS-CoV-2 Variant Classifications and Definitions.
National Human Genome Research Institute. Virus.
British Society for Immunology. Virus replication.
MedlinePlus. Viral Infections.
Centers for Disease Control and Prevention. SARS-CoV-2 Variant Classifications and Definitions.
Ron Sender, Yinon M. Bar-On, et al. The total number and mass of SARS-CoV-2 virions. PNAS. June 3, 2021.
World Health Organization. WHO Coronavirus (COVID-19) Dashboard.
Lisa Maragakis and Gabor David Kelen. Breakthrough Infections: Coronavirus After Vaccination. Johns Hopkins Medicine. November 23, 2021.
Centers for Disease Control and Prevention. CDC streamlines COVID-19 guidance to help the public better protect themselves and understand their risk.
Centers for Disease Control and Prevention. Rates of COVID-19 Cases and Deaths by Vaccination Status.
Centers for Disease Control and Prevention. Stay Up to Date with COVID-19 Vaccines Including Boosters.
Johns Hopkins Bloomberg School of Public Health. The Long History of mRNA Vaccines. 
Centers for Disease Control and Prevention. Understanding mRNA COVID-19 Vaccines.
Centers for Disease Control and Prevention. Understanding Protein Subunit COVID-19 Vaccines.
U.S. Food & Drug Administration. Coronavirus (COVID-19) Update: FDA Recommends Inclusion of Omicron BA.4/5 Component for COVID-19 Vaccine Booster Doses.
Centers for Disease Control and Prevention. Benefits of Getting A COVID-19 Vaccine.

Featured Content


Does Vaccination Protect Against Long COVID?

As many as 50 percent of COVID-19 infections result in lasting symptoms, or long COVID.

Current and Upcoming COVID-19 Vaccine Boosters

Boosters are already available for many, and more options may be coming soon.

COVID-19 Vaccination: Key Terms to Understand

Words to help you stay informed, take precautions, and make good decisions regarding your own health and safety.

5 Things The COVID-19 Vaccine Can Prevent

A COVID-19 vaccine can prevent you from getting the virus. It can also prevent serious illness from an infection.