Effect of Covid-19 Vaccination on Transmission of Alpha and Delta Variants

In this study, 37% of 146,000 PCR-tested contacts of infected persons in England were positive for SARS-CoV-2. Transmission of the alpha variant from twice-vaccinated index patients was rarer than that from unvaccinated index patients (adjusted rate ratio with BNT162b2, 0.32). Vaccine protection waned over time and was more effective against […]

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Effectiveness of the mRNA-1273 Vaccine during a SARS-CoV-2 Delta Outbreak in a Prison

The mRNA vaccines have been shown to be highly effective in preventing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and associated illness,1,2 although recent reports suggest reduced effectiveness against infection with the B.1.617.2 (or delta) variant.3,4 We assessed the effectiveness of the mRNA-1273 (Moderna) vaccine among incarcerated men during a coronavirus […]

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Delta Variant Doubles Hospitalization Risk

People who contract the Delta variant have double the risk of hospitalization, as compared with earlier versions of the coronavirus, according to a new study published Friday in The Lancet Infectious Diseases. Based in England, the large study found that the Delta variant led to a higher rate of hospital admission and emergency care, with […]

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How Well Does COVID-19 Vaccination Protect Against the Delta Variant?

In a U.K. observational study, two doses of the Pfizer-BioNTech and Oxford/AstraZeneca vaccines had 88% and 67% effectiveness, respectively, against the Delta variant. As the Delta (B.1.617.2) SARS-CoV-2 variant fuels a global surge in COVID-19, an urgent clinical question concerns how effective the available vaccines are against this variant. Using […]

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