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Friday, February 26, 2021

First for Covid vaccines: Study shows Oxford jab can reduce transmission

The study by researchers at the University of Oxford is the first to document evidence that any of the Covid-19 vaccines can reduce transmission of the virus.

By: New York Times |
February 4, 2021 10:56:44 am
AstraZeneca vaccine is ready to be used at a homeless shelter in Romford, east London (AP Photo/Frank Augstein)

The vaccine developed by the University of Oxford and AstraZeneca not only protects from serious illness and death, but also substantially slows the transmission of the novel coronavirus, according to a new study.

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The study by researchers at the University of Oxford is the first to document evidence that any of the Covid-19 vaccines can reduce transmission of the virus.

Researchers measured the impact on transmission by swabbing participants every week seeking to detect signs of the virus. If there is no virus present, even if someone is infected, it cannot be spread. And they found a 67 per cent reduction in positive swabs among those vaccinated.

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The results, detailed by Oxford and AstraZeneca researchers in a manuscript that has not been peer-reviewed, found that the vaccine could cut transmission by nearly two-thirds. (‘Single Dose Administration, And The Influence Of The Timing Of The Booster Dose On Immunogenicity and Efficacy Of ChAdOx1 nCoV-19 (AZD1222) Vaccine’, Preprints with The Lancet) The finding underscores the importance of mass vaccination as a path out of the pandemic.

(Pune-based Serum Institute of India (SII) is manufacturing an Indian version of the vaccine — Covishield — under licence from Oxford-AstraZeneca. Covishield and Bharat Biotech’s Covaxin have been administered to around 40 lakh healthcare and frontline workers in India since the country began its mass immunisation programme on January 16.)

British Health Secretary Matt Hancock hailed the results of the study on Wednesday as “absolutely superb.”

“We now know that the Oxford vaccine also reduces transmission and that will help us all get out of this pandemic,” Hancock said in an interview to the BBC. The results, he said, “should give everyone confidence that this jab works not only to keep you safe but to keep you from passing on the virus to others”.

Some scientists looking at the limited information released cautioned that more analysis of the data was needed before such broad conclusions could be firmly stated.

“While this would be extremely welcome news, we do need more data before this can be confirmed and so it’s important that we all still continue to follow social distancing guidance after we have been vaccinated,” said Dr Doug Brown, chief executive of the British Society for Immunology.

The Oxford and AstraZeneca researchers also found that a single dose of the vaccine was 76 per cent effective at preventing Covid-19. The data measured the three months after the first shot was given, not including an initial three-week period needed for protection to take effect.

The encouraging results lend support to the strategy deployed by Britain and other countries to prioritise providing as many first doses of vaccines as possible, setting aside concerns that people will get their second doses later than initially planned.

The latest data do not have bearing on the debate over whether to further space out the doses of the two vaccines authorized in the United States, those from Pfizer-BioNTech and Moderna, since the data on AstraZeneca’s candidate cannot be generalized to other vaccines.


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