Covid Endgame

If Covid keeps spreading until we hit immunity

% of unvaccinated people will catch Covid
% of everyone will end up getting Covid*
% of vaccinated people will get breakthrough Covid

*not including people who get effectively vaccinated after they get sick

You can tweak the assumptions below and see who it will spread to

Final Vaccination Rate %

Vaccination effectiveness %

Final Variant Reproduction Number (Delta Variant is estimated to be R0 = 6 to 8)

Reproduction Number R0 =
Herd Immunity Threshold %

How it spreads

Final Total Immune %
Reached Herd Immunity?
Immune because of Vaccination %
Immune because they got sick %
Chance of getting Sick if Unvaccinated %
Chance of getting sick if Vaccinated %


This page makes the assumption that Covid will continue spreading until we reach herd immunity. This is a reasonable assumption since so far we've seen that if R gets below 1 we relax restrictions until Covid starts spreading again (i.e. R > 1). This will keep happening until R CAN'T be above 1 because we've reached herd immunity.

The herd immunity threshold is related to the reproduction rate:

Immunne threshold = 1 - 1/R0
The delta variant is currently estimated at R=7 or 8. Each variant has a been a bit better at spreading, so we may well find ourselves dealing with a higher R before this is over.

The percentage of folks who are immune is

Immune = (%vax * vaxEffectivness) + %sick - %doubleSafe
People who get sick AND then are vaccinated would count twice if we didn't account for them. In the calculation above I DON'T include these people in the "Immune because they got sick" bucket (unless they also fall in the vaccine was ineffective bucket).

The percentage that get sick is

 1 - Immunity Threshold
and the total vulnerable is
 (1 - vaccinated) + (1 - vaxEffectiveness) * vaccinated 

So the final equation for how likely you are to get sick if unvaccinated
 P(sick if unvaxed) = ((1 - 1/R0) - (vax%*vaxEff))/(1 - (vax%*vaxEff)) 

As you can see from playing around with the sliders, getting to a high vaccination rate is very important if we want to prevent a lot of people from getting sick. We also need to quickly stop Covid so we don't generate new variants with higher R0.