Covishield Effective Against the U.K. Variant

Researchers from the COVID-19 Genomics United Kingdom Consortium, the AMPHEUS Project, and the Oxford COVID-19 Vaccine Trial Group published the results of their exploratory analysis of a randomized controlled trial of the ChAdOx1 nCoV-19 (AZD1222) vaccine against the SARS-CoV-2 variant of concern 202012/01 or the B.1.1.7 variant in the Lancet. The researchers found that the adenoviral vector vaccine, ChAdOx1 nCoV-19 (AZD1222), exhibited reduced neutralization activity against the SARS-CoV-2 U.K. variant, which may affect the current vaccination efforts of multiple countries.

However, the vaccine helped protect against symptomatic disease caused by the novel variant. To arrive at the study findings, the researchers enrolled volunteers who are more than 18 years old. The participants were enrolled in the phase 2/3 vaccine efficacy studies in the U.K. and were randomly assigned to receive the vaccine. The team collected upper airway swabs weekly and if they developed COVID-19 symptoms, including fever, cough, shortness of breath, and loss of smell or taste.

The swabs underwent testing using a nucleic acid amplification test (NAAT) for SARS-CoV-2, and positive samples were sequenced using the COVID-19 Genomics U.K. consortium. A live-virus microneutralization assay against the U.K. variant was performed to measure the participants’ neutralizing antibody responses. The efficacy analysis included symptomatic COVID-19 in seronegative individuals with a NAAT positive swab more than 14 days after a second vaccine dose. The team analyzed the study participants according to the vaccine received. The study findings showed that of the 8,534 participants in the primary efficacy group, 520 participants developed COVID-19.

About 1,466 NAAT-positive nose and throat swabs were collected from the participants. Of these, 401 swabs were sequenced, finding that the laboratory virus neutralization activity was lower against the U.K. variant. Further, the team found that the clinical efficacy against symptomatic NAAT positive infection was 70.4 percent for B.1.1.7 and 81.5 percent for non-B.1.1.7 lineages. Though there is reduced neutralization activity, the vaccine protected against symptomatic disease caused by the B.1.1.7 lineage, hence, vaccination with the Oxford-AstraZeneca vaccine resulted in a reduction in the duration of shedding and viral load, which may reduce viral transmission.

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