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People fully vaccinated with a two-dose coronavirus vaccine have a 50-60% reduced risk of being infected with the delta variant, even asymptomatically, compared to people who are not vaccinated, according to a new study in England .
The study examined nearly 100,000 people who took COVID-19 home swab tests between June 24 and July 12. In this group of samples, 527 people tested positive for the coronavirus and 254 of the samples were genetically analyzed; all samples sequenced were found to be the highly transmissible delta variant.
Once the researchers adjusted for factors such as age, they found that people who received two doses of the vaccine were 49% more likely to test positive for the coronavirus, even without symptoms, than people who were not vaccinated. and that those vaccinated were 59% less likely to test positive with symptoms.
Related: Delta variant: answers to your questions
The conclusions, which were published as pre-publication and have not yet been peer reviewed, are the latest results from Imperial College London’s ‘Real-time Assessment of Community Transmission’, or REACT-1, an ongoing coronavirus surveillance study. .
“These results confirm our previous data showing that two doses of a vaccine offer good protection against infection,” Paul Elliott, REACT program director at Imperial’s School of Public Health, said in a press release. The researchers did not disentangle the effectiveness of specific vaccines.
Their conclusions contradict previous studies. For example, a study conducted by Public Health England found that the Pfizer-BioNTech vaccine was 88% effective against symptomatic disease caused by the delta variant (vaccinated people were 88% less likely to develop symptomatic infection compared to people unvaccinated), compared with about 93% efficacy against the alpha variant, the previous dominant variant. This study found that the two-dose AstraZeneca vaccine was 60% effective against the delta variant, compared with 66% against the alpha variant, Previously reported live science.
Meanwhile, early data from Israel suggested the Pfizer-BioNTech vaccine was 64% effective against symptomatic disease caused by the delta variant, and data from Canada showed it was 87% effective against the disease. symptomatic, according to an internal presentation from the Centers for Disease Control and Prevention. But more recent data from Israel revealed that the effectiveness of the Pfizer-BioNTech vaccine against Delta has slipped to 39% (but is still 88% effective against hospitalization and 91% against serious illness), according to CNBC.
The new study also found that vaccinated people had a lower viral load on average, which means they likely shed less virus and are less contagious than unvaccinated people. This result differs from other data suggesting that the delta variant caused similar viral loads in unvaccinated and vaccinated people who test positive (so-called breakthrough cases), Previously reported live science.
“The delta variant is known to be highly infectious, and therefore, we can see from our data and others that groundbreaking infections are occurring in fully vaccinated people,” Steven Riley, professor of infectious disease dynamics at Imperial College London, said in the statement. “We need to better understand how infectious fully vaccinated people are, as this will help better predict the situation in the months to come, and our findings contribute to a more complete picture of that. “
The researchers also found that the trends between infections and hospitalizations, which had weakened in the spring, were converging again, the statement said. This could be because the dominant variant changes from alpha to delta and more younger people, who may be less likely to be vaccinated, are hospitalized than before.
Young people aged 13 to 24 had the highest infection rate, and people aged 75 and older had the lowest infection rate. About 50% of infections have occurred in people aged 5 to 24, even though they only make up a quarter of the population, Riley told Reuters.
“Today’s report shows the importance of taking personal responsibility by isolating yourself if you are contacted, getting tested for symptoms and wearing face coverings where appropriate,” said UK Health and Social Secretary Sajid Javid in the statement. “I urge anyone who has not yet received a vaccine to get bitten and take both doses – the vaccines are safe and they work.”
Originally posted on Live Science.
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