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Pfizer vaccine only 42% effective in July, study finds

US Rep. Ilhan Omar (D-MN) (L) talks with Speaker of the House Nancy Pelosi (D-CA) during a rally with fellow Democrats before voting on H.R. 1, or the People Act, on the East Steps of the US Capitol on March 08, 2019 in Washington, DC. (AFP photo)
A syringe is filled with a first dose of the Pfizer Covid-19 vaccine at a mobile vaccination clinic at the Weingart East Los Angeles YMCA in Los Angeles, California on August 7, 2021. (AFP photo)

A new study is raising concerns about effectiveness of mRNA vaccines like Pfizer, which has been effective against the fast spreading Delta variant of Covid-19 only 42 percent in US.

The data was from the month of July, when Delta was the dominant variant of the coronavirus, according to the study, which was yet to be certified by peer review.

“This is the kind of surprising finding that needs confirmation before we should accept its validity," said Cornell virologist John Moore, as cited by Axios.

Scientists monitored Pfizer and Moderna vaccines in the Mayo Clinic Health System over time from January to July, concluding that Moderna  was 86 percent effective against infection and Pfizer 76 percent during the period.

Moderna also led Pfizer in preventing hospitalizations at 92 percent compared to Pfizer’s 85 percent.

The effectiveness of both the vaccines against infection dropped significantly in the month of July, with Moderna also falling to 76 percent, according to the study.

“Based on the data that we have so far, it is a combination of both factors," said Venky Soundararajan, a lead author of the study. “The Moderna vaccine is likely — very likely — more effective than the Pfizer vaccine in areas where Delta is the dominant strain, and the Pfizer vaccine appears to have a lower durability of effectiveness.”

The rapid spread of the Delta variant has pushed cases and hospitalizations in the United States to a six-month high.

Pfizer said in a statement that it expects to “be able to develop and produce a tailor-made vaccine against that variant in approximately 100 days after a decision to do so, subject to regulatory approval."

Over 36 million Americans have so far been infected with Covid-19 with over 618 thousand deaths reported since the pandemic began.


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