Skip to Main Content


I keep hearing about COVID-19 variants posing a new threat. What are these variants, and will a vaccine help me avoid them?

Viruses constantly mutate as they are transmitted between people. The virus that causes COVID-19 is no exception. Most of these mutations within the virus are so small as to be of little or no significance; others survive and persist and create new variants of the virus. According to the Centers for Disease Control and Prevention (CDC), multiple variants of COVID-19 are currently circulating globally. These are the leading variants being tracked to date:

  • In April 2021, the Delta, or B.1.617 variant, first discovered in India in October 2020, exploded in India. By month’s end, the nation was recording more than 3,000 deaths daily and more than 1 million new cases of COVID-19 every three days. By mid-June 2021, the variant became responsible for 90% of cases in the U.K. and has been linked with a COVID spike there. By July 2021, the Delta variant became the dominant strain in the U.S., leading to high numbers of cases across the country. It appears to be highly contagious and may cause more severe cases than other variants. A recent U.K. study suggests that people infected with the Delta variant may have different symptoms than those identified previously for COVID-19. As of May 2021, self-reports from patients participating in the UK study showed the number one symptom to be headache, followed by sore throat, runny nose and fever. Cough is rarer as is loss of smell and taste. Health officials cautioned individuals not to dismiss these potential COVID-19 symptoms for a bad cold and to take suitable precautions to reduce potential spread should they appear. While breakthrough infections are still rare, some fully vaccinated people are getting infected, especially with high community transmission across the country. Preliminary data suggests that fully vaccinated people who do become infected with the Delta variant can spread the virus to others, according to the CDC. Because of this new evidence, CDC advises that everyone aged 2 or older, including those fully vaccinated, should wear a mask in indoor public spaces, especially in areas with substantial or high transmission. The vaccines do remain very effective against severe illness, hospitalization, and death. Vaccines are still the best tool to protect yourself and your community against the Delta variant.
  • The Alpha, or B.1.1.7, variant was first identified in the U.K. in the fall of 2020. It has since spread to many other countries; it was first reported in the U.S. in Dec. 2020. This variant has spread more easily and quickly than others. In April 2021, the CDC declared the Alpha variant the most dominant COVID-19 virus strain circulating in the United States. Initial information appears to show that the variant is highly contagious and there are concerns it may be more potentially deadly for those infected although research is continuing.
  • The Beta, or B.1.351, variant, first detected in South Africa, emerged independently from the U.K. variant, though it shares some mutations with it. It was originally detected in Oct. 2020 and was first recorded in COVID-19 cases in the U.S. in Jan. 2021.
  • The Gamma, or P.1, variant, was first identified in Japan in early 2021, and detected in travelers from Brazil during a routine screening at an airport. It was first detected in the U.S. in late January 2021. This variant contains a set of mutations that may affect its ability to be recognized by antibodies.

What We Know (from the CDC)

  1. Variants are expected. The best way to slow the emergence of new variants is to reduce the spread of infection by taking measures to protect yourself including getting a COVID-19 vaccine when available.
  2. Vaccines keep you from getting sick, being hospitalized, or dying from COVID-19.
  3. All COVID-19 tests can detect all variants, but they will not tell you which variant you have.

What We Do Not Know

Evidence is limited on how the new COVID-19 variants will affect how COVID-19 vaccines work in real-world conditions. CDC has systems in place to monitor how common these variants are and to look for the emergence of new variants. CDC will continue to monitor variants to see if they have any impact on how COVID-19 vaccines work in real-world conditions.