The new Delta COVID-19 virus variant, which was first detected in India, has so for accounted for more than 6% of all infections in the United States, says the US Centers for Disease Control and Prevention (CDC)

This highly contagious strain of the coronavirus may be responsible for over 18% of cases in some Western states.

The Delta variant is called B.1.617.2, which is spreading rapidly in the U.K., now becoming the dominant strain there.

In the U.K., the strain is responsible for more than 60% of infections and causing surges in some parts of England, according to NPR Health.

Dr. Anthony Fauci, the nation’s top infections disease expert and director of the National Institute of Allergy and Infectious Diseases (NIAID) said, “We cannot let that happen in the United States.”

On Tuesday, Dr. Fauci spoke at a White House COVID briefing, warning that the Delta strain may be associated with the more severe disease and a greater risk of hospitalization.

However, the good news is the currently available vaccines can protect people against the Delta strain.

A new study by the researcher of Public Health England has shown that the two-dose Pfizer-BioNTech vaccine is 88% effective against the infection caused by the Delta variant compared with 93% efficacy against the Alpha variant, the variant first detected in the U.K.

The efficacy of the vaccine declined to 33% after just one dose, according to NPR.

Dr. Fauci has urged people who have received the first dose of the Pfizer or Moderna vaccines to make sure to get their second dose. “And for those who have still not been vaccinated yet, please get vaccinated,” he advised.

The NIAID director also explained that vaccination is the best way to protect yourself from the deadly virus, adding that immunization could stop this variant from spreading and becoming dominant in the U.S. He said there is research underway on the use of booster doses of the vaccine for both the original COVID-19 virus and its new variants. However, he did not specify when they will be available.