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Protection against death (mortality)
Vaccine effectiveness against death (mortality) from Omicron in those aged over 50 (it is too early to produce accurate data for those aged under 50):
- After two doses: 59% after twenty-five weeks
- After a booster dose: 95% after two weeks
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Protection against severe disease requiring hospitalisation from Omicron
- After two doses of any vaccine: 25-35% protection after twenty-five weeks
- After a Pfizer booster: around 90%, dropping to around 75% after ten to fourteen weeks
- After a Moderna booster: 90-95% up to nine weeks after vaccination
Hospitalisations prevented: Latest analysis estimates the boosters alone prevented 105,600 hospitalisations in those aged 25 and over in England between December 13 2021 and February 6 2022.
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Protection against symptomatic disease (mild infection)
- After two doses of AstraZeneca: around 50% protection, waning to almost 0% from twenty weeks
- After two doses of Pfizer or Moderna: 65-75% protection, waning to around 10% by twenty-five weeks after the second dose
- After a booster dose: 65-75% protection after two to four weeks, waning to 30-40% after fifteen weeks
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Protection against infection (including asymptomatic infection)
Vaccine effectiveness against infection from Delta (including asymptomatic infection):
- After two doses of AstraZeneca: Estimated at around 50% after two months
- After two doses of Pfizer: Estimated at around 81% after two months, waning to around 46% after six months
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Prevention of transmission
Effectiveness of the vaccines against transmission of the Delta variant:
- After two doses of AstraZeneca: Estimated at 42%
- After two doses of Pfizer: Estimated at 31%
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Additional vaccine protection for those with prior infection (infection-derived immunity)
Early evidence shows that getting vaccinated after infection provides significantly higher levels of protection against reinfection. Protection against reinfection from Omicron:
- No vaccination and prior infection: Estimated at 44%
- Prior infection and three vaccine doses: Estimated at 71%