Oxford and Pfizer Vaccines 'Highly Effective' in Reducing Severe COVID-19

Peter Russell

March 02, 2021

Both the Pfizer/BioNTech and the AstraZeneca/Oxford vaccines were highly effective in reducing COVID-19 among older people, new data revealed.

The preprint of a study submitted by Public Health England (PHE) suggested that since January 4, approximate protection against symptomatic COVID-19 for people aged 70 and over after a single dose of vaccine ranged between:

  • 60% and 70% for the Pfizer/BioNTech vaccine

  • 60% and 75% for the AstraZeneca/Oxford vaccine

Fewer Hospital Admissions

As well as protecting against symptomatic disease, people vaccinated with one dose of the Pfizer/BioNTech BNT162b2 had a 44% lower risk of emergency hospital admission and a 51% lower mortality risk compared with unvaccinated cases.

People who had been vaccinated with one dose of the AstraZeneca/Oxford ChAdOx1 had a 37% lower risk of emergency hospitalisation, although the confidence interval for this was wide at between 3% and 59%.

There was insufficient data to show the Oxford vaccine's effect on mortality due to its later rollout.

Both vaccines currently deployed in the UK were approximately 80% effective at preventing hospital admission in those aged 80 and over around 3 to 4 weeks after a single dose, the study suggested.

Effective Against UK Variant

A single dose of either vaccine provided "significant protection" against COVID-19 lasting at least 6 weeks, including against the UK/Kent 'variant of concern', VOC 202012/01, the authors concluded.

Dr Mary Ramsay, head of immunisation at PHE, and one of the study authors, said: "This adds to growing evidence showing that the vaccines are working to reduce infections and save lives.

"While there remains much more data to follow, this is encouraging, and we are increasingly confident that vaccines are making a real difference."

The authors of the study, which has yet to be peer reviewed, said their data supported the UK's decision to space vaccine doses 12 weeks apart.

'Encouraging' Results

Commenting to the Science Media Centre, Paul Hunter, professor in medicine at the University of East Anglia, said: "This study gives very clear evidence that the UK strategy of delaying the second dose to allow more people to be protected by a first dose was the right approach to reduce the pressure on the NHS and reduce the number of deaths in this age group.

"This study provides strong reassurance that, as expected, the vaccine works well against the Kent variant. However, it is too early to judge how effective the vaccine will be against the South African, Bristol, or Brazil variants."

Deborah Dunn-Walters, professor of immunology at the University of Surrey, described the findings as "encouraging", but said "we still have much more that we need to understand about how effective these vaccines are against transmission and against some of the newer variants, along with needing a deeper immunological understanding of the components of immune memory generated".

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