This method shows the impact by calendar year, e.g. the number of people who would have died in a
given year but whose deaths were averted due to vaccination given at any previous time. This is also
known as "cross-sectional impact". While the resulting estimates are intuitively easy to understand,
they fail to represent the long-term future impact of vaccination on individual disease risk. In
addition, the impact estimates cannot be linked to specific vaccination activities.
Year of birth
This method shows the impact for each birth cohort, e.g. the number of deaths prevented in a cohort
born in a given year, over the course of their lifetime. We calculate impact for birth cohorts from
2000 to 2030, and consider the lifetime up to 2100. This is also known as "lifetime impact" or
"cohort impact". This approach is appropriate for capturing the direct effects of vaccination in
protecting the immunised individual. However, indirect effects of vaccination (acting via herd
immunity) play out across the whole population.
Year of Vaccination
This is the approach used by VIMC to estimate vaccine impact by year of vaccination. It can be used
to easily determine the efficacy of a particular vaccination campaign.
A technical description of our impact estimation methods can be found at