Pfizer-BioNTech vaccine provides high levels of protection from the first dose
https://www.gov.uk/government/news/first-real-world-uk-data-shows-pfizer-biontech-vaccine-provides-high-levels-of-protection-from-the-first-dose
https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3790399
BNT162b2 mRNA
Vaccine effectiveness in healthcare worker
Prospective cohort study of staff undergoing regular asymptomatic testing.
The SIREN study
N = 29,378
2 weekly intervals
Records symptoms, PCR and antibody test results
Therefore symptomatic and asymptomatic infections
Hazard ratios to compare time
Infection in unvaccinated and vaccinated groups
Findings, 5th February 2021
People who were antibody negative on recruitment
A single dose of BNT162b2 vaccine, effectiveness of 72%
21 days after first dose
Rising to 86% seven days after two doses
Conclusion
Vaccine effectively prevents both symptomatic and asymptomatic infection in working age adults
Cohort was vaccinated when the dominant variant in circulation was B1.1.7
Consistent data
Israel, Norwich Medical School
Pfizer COVID-19 BNT162b2 vaccine, after a single dose, ‘real-world’
At day 21
Vaccine effectiveness, 91%
After day 21
Remained at 90%
Expected to last form 9 weeks to 6 months
Vaccine effectiveness seems to be better at reducing severe disease that at reducing mild disease
Public health Scotland
Fourth week after first dose, reduced risk of hospitalisation
Pfizer, down 84% (n = 650,000)
Oxford-AstraZeneca, down 94% (n = 490,000)
Combined reduction in over 80s
Vaccination associated with 81% reduction in hospitalisation risk in the fourth week
Source