[ad_1]
A study published by a large number of U.S. health workers found that Covid messenger RNA vaccines were 66% effective against Delta.
These vaccines include Pfizer and Moderna, which have been given to the majority of people, who previously claimed to have a 91% effectiveness rate.
The Centers for Disease Control and Prevention (CDC) has looked at the actual performance of both vaccines since their first authorization among healthcare workers, first responders and other frontline workers.
Thousands of workers in six states have been tested every week and upon onset of symptoms of Covid-19, allowing researchers to estimate effectiveness against symptomatic and asymptomatic infections.
By examining the rate of infections among vaccinated and unvaccinated people and the length of time they were followed, the vaccine’s efficacy was estimated to be 91% during the initial study period from December 14, 2020 to December 10, 2020. April 2021.
But in the weeks leading up to August 14, when the ultra-contagious Delta variant became dominant, the effectiveness dropped to 66%.
The authors of the report said there were a number of caveats, including that vaccine protection could wane over time anyway, and the 66% estimate was based on a study period. relatively short with few infections.
“While these interim results suggest a moderate reduction in the effectiveness of COVID-19 vaccines in preventing infection, the sustained two-thirds reduction in the risk of infection underscores the importance and continued benefits of COVID vaccination. -19 “, they said.
A number of studies have now concluded that the vaccine’s efficacy has dropped against Delta, although the precise level of this drop differs from article to article.
Protection against critical illness appears more stable, exceeding 90 percent, according to a recent CDC study of patients in New York City.
Another CDC study of Los Angeles patients released on Tuesday and conducted from May 1 to July 25 showed that unvaccinated people were 29.2 times more likely to be hospitalized with Covid-19 than those vaccinated, which corresponds at about 97% efficiency.
Delta became the dominant variety in the United States in early July.
According to a recent article in the journal Virological, the amount of the virus found in the first tests of patients with the Delta variant was 1,000 times that of patients with the first wave of the virus in 2020, greatly increasing its contagiousness.
(With contributions from agencies)
[ad_2]
Source link
