According to the latest data published in a study this Tuesday August 24, 2021 by the American health authorities, Pfizer and Moderna vaccines effectiveness drops from 91% to 66% against the Delta variant. In the U.S. the Delta variant – more contagious than the previous strains – has been dominating since the beginning of July and is causing 98% of the contaminations.
The study was carried out in thousands of hospital staff members and care centers in 6 states in the U.S. Tested weekly, participants have been given the Pfizer and Moderna vaccines. The study shows that between December and April 2021, both serums were 91% effective, according to data published by the CDC.
But since the Delta variant has taken over in the United States, their effectiveness dropped from 91% to 66%. “Although these interim findings suggest a moderate reduction in the effectiveness of COVID-19 vaccines in preventing infection, the sustained two thirds reduction in infection risk underscores the continued importance and benefits of COVID-19 vaccination”, the study authors specify.
The latter assess the vaccine effectiveness fades over time, as we now know. Furthermore, the American health authorities have announced a booster-shot vaccination campaign for third doses starting from mid-September 2021, targeting at American adults who have been given the second dose 8 months earlier.
