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    Home > Active Ingredient News > Infection > NEJM: Impact of Covid-19 vaccination on transmissibility of Alpha and Delta variants

    NEJM: Impact of Covid-19 vaccination on transmissibility of Alpha and Delta variants

    • Last Update: 2022-04-18
    • Source: Internet
    • Author: User
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    Prior to the emergence of the B.
    1.
    617.
    2(delta) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination reduced transmission among individuals infected with SARS-CoV-2 , possibly by reducing viral load
    .


    Although vaccination still reduces the risk of infection, the similar viral load in vaccinated and unvaccinated individuals infected with the delta variant raises questions about the extent to which vaccination prevents its spread


    Infect

    In a study published today in the top medical journal NEJM, researchers conducted a retrospective observational cohort study involving adults infected with SARS-CoV-2 using exposure testing data from England
    .


    The researchers used multivariate Poisson regression to explore the associations between transmission and the vaccination status of contacts and to determine how these associations varied with B.


    Of 146,243 contacts of 108,498 infected patients, 54,667 (37%) tested positive for SARS-CoV-2 by polymerase chain reaction (PCR)
    .


    In patients infected with the alpha variant, two vaccinations with BNT162b2 or ChAdOx1nCoV-19 (also known as AZD1222) were independently associated with a lower rate of PCR positivity among contacts compared with unvaccinated (adjusted BNT162b2 rate of 0.


    Vaccine-associated reduction in transmission of delta variants was less than that of alpha variants; the extent to which the transmissibility of the delta variant was reduced after two BNT162b2 vaccinations (adjusted ratio ratio, 0.
    50 compared with unvaccinated; 95% CI, 0.
    39 to 0.
    65) than Greater after two ChAdOx1nCoV-19 vaccinations (adjusted ratio ratio, 0.
    76; 95% CI, 0.
    70 to 0.
    82)
    .


    Changes in circulating threshold (Ct) values ​​(viral load) in patients explained a 7% to 23% reduction in vaccine-related transmissibility for both variants


    Thus, vaccination was associated with reduced transmissibility of the delta variant compared with the alpha variant, and the efficacy of vaccination decreased over time
    .


    The Ct value of PCR at the time of patient diagnosis only partially explains the decreased transmissibility


    Vaccination was associated with reduced transmissibility of the delta variant compared to the alpha variant, and the efficacy of vaccination decreased over time


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