So there is no such thing as natural immunity?
We all have an immune system. Sometimes it goes wrong and either doesn't do it's job properly or does it too much and attacks the body.
But for the vast majority we have an immune system, this is series of cells that do certain jobs.
An analogy I've used before is that it is an army.
Very disciplined and good at marching and doing routine things so that if you pick up bacteria from the handle of a supermarket trolly and then that bacteria gets into your mouth (maybe you tried something from the delli counter) your immune system works to stop that becoming an infection.
The army also recognises and defends against things that are local ie endemic. Sometimes some immunity is genetic. People from the village of Eyam in Derbyshire are often naturally immune to plague. Fascinating reading if you have a couple of hours spare.
When your body encounters a disease this is like the army being attacked by a new weapon or new way of fighting. The army hasn't seen this before so it has to identify what it is and train soldiers so fight this particular enemy. But while it is identifying and planning you are getting more ill.
Some times outside help in the form of antibiotics will come into the system but that can't be relied upon.
Immunisation / vaccination is like a training exercise. It gives your body the chance to identify and train specialist soldiers so if the attack happens the immune system is ready and can counter attack.
So there are three ways to get immunity.
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Inherit it from a parent, this only applies to one or two very specific diseases, and not things we encounter everyday. There is also some immunity passed from mother to child, but this wears off quickly.
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Encounter the 'wild' disease. This may mean being ill, it may also mean you have the disease but don't know because your immune system is being efficient. Most people who have had polio don't know it.
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Encounter the disease in a modified/harmless form ie vaccination/immunization.
Obviously option 1 is the best, but how often do we encounter plague in western Europe?
Option 2 is the nasty one, any of the diseases we vaccinate against are nasty, with the exception of rubella they can all leave you severely disabled if they do not kill you. Rubella will protect your daughter's unborn child if she chooses to have children. It will also mean she cannot infect a pregnant woman.
Option 3 is the only realistic option.
It is possible your daughter has encountered some of the diseases and gained immunity, but very very unlikely. When did you last hear of diphtheria?