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First real-world UK data show Pfizer-BioNTech vaccine provides high levels of protection against COVID-19 from the first dose.

Early data from a Public Health England (PHE) study called SIREN that staff at Buckinghamshire Healthcare NHS Trust (BHT) have been taking part in show a promising impact on infection in healthcare workers aged under 65. Data show one dose reduces the risk of catching infection by more than 70%, rising to 85% after the second dose.


Healthcare workers at BHT are tested for COVID-19 every 2 weeks – whether or not they have symptoms. This suggests the vaccine may also help to interrupt virus transmission, as you cannot spread the virus if you do not have infection.

PHE’s analysis of routine testing data also shows that one dose is 57% effective against symptomatic COVID-19 disease in those aged over 80. This effect occurs from about three to four weeks after the first dose.

Early data suggest the second dose in over 80s improves protection against symptomatic disease by a further 30%, to more than 85%.

Hospitalisation and deaths rates are falling in all age groups – but the oldest age groups are seeing the fastest decline since the peak in mid-January. 


Early data suggest vaccinated people who go on to become infected are far less likely to die or be hospitalised. Overall, hospitalisation and death from COVID-19 will be reduced by over 75% in those who have received a dose of the Pfizer-BioNTech vaccine.

The risk of dying in those aged over 80 is less than half (56%) in vaccinated cases compared to unvaccinated cases, at least 14 days after receiving the first dose.

Those over 80 who develop COVID-19 infection after vaccination are around 40% less likely to be hospitalised than someone with infection who has not been vaccinated.

These high levels of protection are also seen against the variant of concern (B.1.1.7) first identified in South East England in December 2020.


While the data on infection, hospitalisation and death are promising, PHE will continue to observe these trends closely over the coming months to ensure firmer conclusions can be made.

PHE is also monitoring the real-world impact of the AstraZeneca vaccine and will publish these findings in due course – but early signals in the data suggest it is providing good levels of protection from the first dose.



For more information about the SIREN study, please visit the study website here.


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