A doctor in a protective suit taking a nasal swab from a person to test for possible coronavirus infection

The amount of people in the Untied States infected by COVID-19 variants exceeded 11,000 at the end of March.

There are three variants the Centers for Disease Control and Prevention is concerned with right now: B.1.1.7, B.1.351, P.1. More than 11,500 people had tested positive for having been infected by the COVID-19 variant B.1.1.7 through March 30, the last time the CDC provided an update before this writing. Another 312 and 172 people have been infected by the B.1.351 and P.1 variants, respectively.

The CDC says these variants are especially problematic because they cause mutations to the virus' genome that make the disease more severe and easier to spread. It also impacts the effectiveness of the vaccines that are being provided.

Michigan and Florida are the two states that have been impacted the most by the B.1.1.7 variant, according to the CDC. Georgia, Minnesota, Massachusetts and California also report at least 500 cases where someone was infected by that particular variant.