ROCHESTER, N.Y. (WROC) — The Centers for Disease Control and Prevention estimates that the delta variant is now the dominant strain of coronavirus in the U.S.

To answer delta variant questions, Rochester Regional Health infectious disease expert Dr. Ed Walsh held a briefing with media Friday where he said a small portion of local COVID-19 cases have been identified as delta variants.

“I have not seen the data personally, but I have been told that based on the data that’s come out of Wadsworth Laboratory that delta virus is in Rochester, that it represents a small but appreciable percentage of cases that are occurring locally,” Dr. Walsh said.

The variant was first identified in India in December of 2020. It was detected in the U.S. in March. According to the World Health Organization, Delta is estimated to be about 55% more transmissible than the alpha variant, which originated in the United Kingdom.

The CDC reports the delta variant now accounts for more than 51% of coronavirus cases in America.

In some states where the vaccination rates are lower, the delta strain accounts for more than 80% of new infections, such as in Iowa, Kansas, and Missouri, the CDC reports.

Health experts say the good news is that the vaccines being used in the U.S. are highly effective against the virus.

“Fortunately we’re not seeing too much coming into the hospitals right now and I think in large part that’s because we’ve done pretty well vaccinating our most vulnerable, elderly, and high risk individuals,” Dr. Walsh said. However, it shouldn’t give us too much comfort because clearly the virus is here. There’s no reason it won’ do what it’s doing elsewhere, it is more transmissible so therefore it will spread. It will tend to dominate the previous virus that had come out of the U.K. that dominated Rochester for several months and it may well become the most dominate one here because it is much more transmissible.”

Dr. Walsh says the emergence of the delta variant is another reason to push for more vaccination.

“It will evolve slower as more and more people get immune because there will be less opportunity to grow and spread so therefore the number of variants may well diminish over time,” Dr. Walsh said.

Watch the full briefing

Check back with News 8 WROC as we will continue to update this developing story.