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Risk of death reduces after COVID-19 vaccine but protection wanes after six months

The risk of death from COVID-19 decreases significantly after vaccination but this protection diminishes after six months, providing evidence for continued booster doses targeting those at highest risk, a new study has found.

Researchers from the UK Health Security Agency (UKHSA) analysed more than 10 million cases of COVID-19 in adults between May 2020 and February 2022. Their findings are published in the Journal of the Royal Society of Medicine (JRSM).

The Case Fatality Risk (CFR) - the proportion of COVID-19 cases that resulted in death - was highest among older people during the pandemic. When cross-referenced with vaccination status, it revealed a clear association between vaccination and reduced mortality. Notably, the study highlights a crucial timeframe - within six months of the last vaccine dose - when CFR was consistently at its lowest across all age groups. After this, the protective benefit began to wane and CFR increased.

The research underscores the success of the COVID-19 vaccination programme in reducing mortality rates.

Among adults over 50, CFR was 10 times higher in the unvaccinated (6.3%) compared to those who had been vaccinated within six months prior to testing positive (0.6%). The study also reveals a steep decline in CFR in early 2021, aligning with the initial vaccine rollout.

Florence Halford from the UKHSA’s COVID-19 Vaccines and Epidemiology Division said: "COVID-19 Case Fatality Risk reduced following vaccination, with the lowest risk of death following infection observed in the six months after vaccination. This provides some evidence to support a continued booster campaign targeting high risk groups."

Read the full paper

Photo credit: Alex Yeung -

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