COVID-19 is the disease caused by a type of coronavirus, which is a family of viruses common in humans and many different animals. Viruses in this family can cause respiratory illnesses ranging from the common cold to more severe diseases. Cases of COVID-19, in particular, can be mild, but others can be more severe and sometimes deadly—especially for older adults or those living with other chronic health conditions.
The original virus that causes COVID-19 has mutated into different strains called variants. Different variants may spread more easily, may cause more serious disease, and may not respond as well to treatment. Delta and Omicron are the current variants of concern in the United States.
Therefore, it is important to continue to take steps to prevent the spread of COVID-19. So far, the COVID-19 vaccines provide some protection against the known variants and vaccination including a booster is still the best protection available. However, no vaccine provides 100% protection against COVID-19 and its variants. Therefore, even people who are vaccinated should keep following recommended steps to protect themselves and others.
Last Updated December 2021