An analysis by Public Health England (PHE) exploring the impact of COVID-19 vaccines on mortality has found that, from December 2020 to the end of February 2021, England’s COVID-19 vaccination program prevented 6100 deaths in individuals aged 70 and older.
Vaccine rollout in the UK and England
The first COVID-19 vaccine authorized for human use in the UK was the Pfizer–BioNTech vaccineon December 2, followed closely by Oxford University–AstraZeneca’s ChAdOX1 later that month. Just six days after the first approval of BNT162b2, the first dose was given. Since then, over 30 million people in the UK have received their first dose.
From the beginning of the COVID-19 vaccine rollout, PHE have monitored the program in England in order to assess the real-world efficacy of each vaccines. In its latest analysis, PHE sought to estimate the impact of vaccination with either of the two available vaccines on reducing COVID-19-related deaths in individuals aged 70 and above.
What were PHE’s findings?
To approximate the daily impact of vaccination on deaths, PHE’s estimate of vaccine effectiveness against mortality was multiplied by vaccine coverage. The resulting number was then used to divide the number of observed deaths in order to estimate the expected deaths in the absence of vaccination. Calculations also considered the time taken for individuals to develop an immune response from the COVID-19 vaccine and thus for vaccination to have an impact on observed deaths.
The results estimate that vaccination prevented 5900 and 200 deaths in individuals aged 80 and above and in the 70-79 age bracket, equalling a total of 6100 deaths prevented. Dr Mary Ramsay, PHE’s head of immunization, called this “a striking impact on mortality” in a recent press release. PHE’s calculation is also close to the estimate of 6592 deaths prevented that was made by Warwick University using a different model that is described in PHE’s report.
Some experts have called into question the methods by which PHE calculated the impact of vaccination on mortality. “The paper is light on detail,” commented Professor Sheila Bird, former program leader at the MRC Biostatistics Unit, University of Cambridge. “In particular, how the weighting of ‘vaccine impact’ changed over time because the mix of vaccine-types changed; and whether impact was differentiated by whether the second Pfizer/BioNTech dose was delivered on the 1/22 days randomized-trial schedule.”
Dr Julian Tang, honorary associate professor at the University of Leicester and consultant virologist, compared the relative impact of the program to that of England’s early lockdowns: “The fact that the COVID-19 vaccines reduce deaths in those vaccinated is not surprising – but the size of the effect (four million doses given over three months Dec-Feb to save 6100 lives), seems relatively small compared to the impact of earlier interventions and lockdowns over a similar three month (Mar-May 2020) period during the earlier part of the pandemic – to reduce the spread of the virus in the first place."
PHE’s report concludes that the findings demonstrate that the vaccination program is having a more significant effect on the severity of COVID-19 than national lockdowns. However, it also notes that the true impact of vaccination on COVID-19-related deaths may only be known with a future resurgence of SARS-CoV-2.