WASHINGTON: The effectiveness of the Covid-19 vaccine among front-line workers fell to 66% after the Delta variant became dominant, compared to 91% before it appeared, according to a report from the centers and prevention of US diseases.
The vaccine is still a protector, the CDC word, and findings must be interpreted carefully, because the effectiveness of the vaccine may decrease from time to time and expectant efficacy estimates.
“Although the temporary findings show a moderate reduction in the effectiveness of the Covid-19 vaccine in preventing infection, two-third-third-thirds reduction in the risk of infection underlining the sustainable interests and benefits of Covid-19 vaccination,” the researchers wrote in the morbidity of the agency and reports of weekly mortality.
These findings echo the previous evidence of Israel and the UK suggested the Covid vaccine lose potential in preventing infection from time to time as a Delta variant spread.
The results of this study and others will be under supervision next week because CDC advisors weigh on the Biden administration plan to manage a booster dose for most vaccine recipients in the US.
Booster’s campaign, still awaiting food and medicine administration registration, arranged to start September 20.
The CDC Advisory Committee on immunization practices will consider the extra dose plan during a two-day meeting that began Monday.
The findings of effectiveness that are reduced when Delta is a dominant virus strain equipped with an important warning: the estimation range is very uncertain.
The researchers reported 95% confidence that the efficacy was between 26% and 84% in that period.
Observational studies track more than 4,000 health workers, first respondents, and other frontline personnel in eight US locations in six states from December 2020 to 2021.
They tested every week for Covid infection, and around 83% vaccinated.
About two-thirds of those who were vaccinated had received PFIZER Inc.-Bontech SE Shot, 2% received Johnson & Johnson, and the rest received a modern vaccine.
Overall, vaccination is estimated at 80% effective in preventing infection during the study period.