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VERIFY: How effective are the vaccines against the Delta variant?

The Delta variant has become the dominant strain of coronavirus in the U.S. How are the vaccines doing against it?

WASHINGTON — The Delta variant of coronavirus has quickly become the dominant strain of the virus in the United States. Early studies show it could be two times more contagious than the original virus.

The Verify team received an email asking, “How effective is the Johnson & Johnson shot against the Delta variant?”

We went a step further and looked at all the vaccines.


How effective are the vaccines against the Delta variant of coronavirus?

Our Sources: 

Two epidemiologists from Johns Hopkins University Dr. David Dowdy and Dr. Priya Duggal. We also used research studies released from the companies that developed the COVID-19 vaccines.


The research, so far, shows the vaccines have similar levels of effectiveness to the Delta variant as they did against the original strain of the virus.

What We Found:

“It's important to know that there's no evidence that current vaccines are any less effective against the Delta variant,” Dr. Dowdy said.

We first looked at the Johnson & Johnson vaccine. According to the most recent research, which was a small study conducted by the company, the vaccine is at least 60% effective against the Delta variant. Which was similar to its effectiveness against the original virus.

Pfizer also recently released its research on the Delta variant. This study found after two doses, the Pfizer vaccine was 84% effective.

Moderna has not yet released its study on vaccines effectiveness, but our experts said they expect similar results to the Pfizer study.

Our experts point out, so far, all of the vaccines appear to be helpful against the Delta variant.

“In the U.S., where the Delta variant accounts for most of our infections, we're seeing that the vast majority of cases serious cases, and especially deaths are occurring in people who are not vaccinated,” Dr. Dowdy said.

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