Skip to content
COVID-19 Population Immunity Calculator
COVID-19 Population Immunity Calculator
Calculations
More
Share
Explore

icon picker
COVID-19 Population Immunity Calculator

​
YG
Youyang Gu
This calculator attempts to estimate the true proportion of a population that have immunity against COVID-19. Given just the natural infection rate and vaccination rate, one can estimate the total population immunity against COVID-19 in any region.
Traditional immunity estimates only look at a single metric: vaccination rate. But there are two main issues with this:
Not all vaccinated individuals are protected (since vaccine efficacy is not 100%)
They do not take into account acquired immunity from those who have previously been infected with COVID-19. This calculator attempts to correct for these two major issues to give a more accurate representation of the total population immunity.
For more details:
covid19-projections.com/path-to-herd-immunity
⁠
⁠
⁠
Click here
⁠
for the spreadsheet behind the calculators (including raw formulas).

Inputs

Natural infection rate (% already infected):
000
25
⁠
% (US reference: ~30-40%)
Total population vaccination rate (with 1+ dose):
000
65
⁠
% (US reference: ~55%)
Vaccination rate among previously infected individuals (should be slightly lower than the total vaccination rate):
000
55
⁠
% (US reference: ~45%)

Total Population Immunity:
66%
⁠
⁠

Note: Even if population immunity is at or near herd immunity, local outbreaks are still possible (and even likely given new variants). Even if protection is not 100%, vaccines are near 100% effective at protecting against hospitalizations & deaths.

Efficacy Constants

These are best estimates based on the latest research, taking into account the variants.
Average vaccine efficacy:
000
85
⁠
⁠
Average natural immunity efficacy:
000
85
⁠
⁠
Average vaccine + natural immunity efficacy:
000
95
⁠
⁠
Want to print your doc?
This is not the way.
Try clicking the ⋯ next to your doc name or using a keyboard shortcut (
CtrlP
) instead.