UK ONS: Natural infection by Covid provides a similar level of protection to two vaccine doses

UK Office of National Statistics: “Two vaccination doses provided a similar level of protection to previous natural infection during the Delta-dominant period”

Modelled risk ratios of testing positive for COVID-19 by COVID-19 vaccine exposure, when the Delta variant was dominant, UK, 17 May to 14 August 2021

 

  • there was no evidence that the reduction in risk of infection from two doses of either vaccine differed from that of previous natural infection
  • two doses (14 days or more previously) of Pfizer-BioNTech reduced the risk of testing positive by 73% (95% confidence interval: 70% to 76%) in the Delta period, compared with 80% (95% confidence interval: 74% to 85%) in the Alpha period​
  • two doses (14 days or more previously) of Oxford-AstraZeneca reduced the risk of testing positive by 62% (95% confidence interval: 58% to 66%) in the Delta period, compared with 76% (95% confidence interval: 62% to 85%) in the Alpha period
  • the reduction in risk 14 days or more after second dose was significantly higher with Pfizer-BioNTech compared with Oxford-AstraZeneca​
  • the risk reduction from two doses of either vaccine was greater than from one dose (21 days or more previously)

 

UK ONS report:  Coronavirus (COVID-19) Infection Survey Technical Article: Impact of vaccination on testing positive in the UK: October 2021

 

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