Early estimates of the effectiveness of the Pfizer and Oxford AstraZeneca vaccines by Public Health England. Data shows efficacy against symptomatic COVID disease (confirmed by positive test). This data was based upon people vaccinated who wee aged 70or over.
Pfizer vaccine demonstrates an estimated Efficacy of 61% between 28-34 days after 1st dose. Oxford AstraZeneca vaccine has an estimated Efficacy of 73% from day 35 onwards.
Some of these estimates have fairly wide confidence limits but it is undeniably brilliant news to see both vaccines being so effective after just a single dose.
On top of the protection against symptomatic disease, cases who had been vaccinated with one dose of Pfizer had an additional 43% lower risk of emergency hospitalisation and an additional 51% lower risk of death.
Cases who had been vaccinated with one dose of Oxford AstraZeneca had an additional 37% lower risk of emergency hospitalisation. There was insufficient follow-up to assess the effect of Oxford AstraZeneca vaccine on mortality due to the later rollout.
Combined with the effect against symptomatic disease, this indicates that a single dose of either vaccine is approximately 80% effective at preventing hospitalisation and a single dose of Pfizer vaccine is 85% effective at preventing death with COVID-19.
The report concludes that a single dose of the Pfizer vaccine is approximately 60-70% effective at preventing symptomatic disease in adults aged over 70 in England and 2 doses of this vaccine are approximately 85-90% effective. The effect of a single dose of the Oxford AstraZeneca vaccine against symptomatic disease was approximately 60-75% after a single dose, with insufficient data available to determine effectiveness of two doses of this vaccine.
Pre-print of report can be found here >> https://khub.net/documents/135939561/430986542/Early+effectiveness+of+COVID+vaccines.pdf/ffd7161c-b255-8e88-c2dc-88979fc2cc1b?t=1614617945615