CDC says delta variant now makes up majority of US cases

The delta variant made up the majority of U.S. COVID-19 cases for the first time for the two weeks ending July 3, according to new data from the Centers for Disease Control and Prevention.

Rapid growth: Illustrating the quick rise in the prevalence of the variant, the proportion of U.S. COVID-19 cases that were the delta variant rose from 30.4 percent for the two weeks ending June 19 to 51.7 percent for the two weeks ending July 3.

The delta variant is highly transmissible, and experts are warning that it could cause localized spikes in cases in areas of the country with low vaccination rates, such as the South.

This is important: Experts say the vaccines are still highly effective against the variant. A British study in May found that the Pfizer vaccine was 88 percent effective after two doses.

An Israeli study this week showed lower effectiveness, at 64 percent, but the study has drawn some skepticism from experts, who say it could be an outlier.

The best way to be protected against the delta variant is still to get vaccinated, experts say.