Why vaccine protection changes over time
Vaccine-derived immunity is generally strongest shortly after a dose and gradually wanes over the following months as antibody levels decline, even though other parts of the immune system (like memory cells) can provide longer-lasting partial protection.
How this calculator works
This tool starts from an illustrative baseline effectiveness associated with your number of doses, then applies an exponential decay model with an approximate 6-month half-life to represent typical waning, similar in shape to patterns reported in vaccine effectiveness studies. A modest floor is applied for anyone vaccinated, reflecting that some protection (particularly against severe disease) tends to persist longer than protection against infection.
These figures are simplified, illustrative estimates for general education, not a personalized medical prediction. Actual immunity depends on the specific vaccine, your health status, prior infections, and the circulating variant. Consult a healthcare provider for guidance on boosters or your personal risk.