Because immunity through antibodies is specific (flu antibodies only protect against flu) the idea that – the more harmful, germs we encounter the “stronger” our immune system – is flawed.  However, in recent years evidence has begun to emerge that exposure to an infection can protect against other unrelated infections.

Some recent evidence suggests that some pathogens (if you survive them) may somewhat increase the activity of the innate immune system.  However, exposure to potentially lethal infections like measles must be regarded as a very risky strategy for obtaining protection from other infections. Of potential clinical value, is new data suggesting that this nonspecific priming of the immune system can be exerted safely by vaccines but much more work is needed to develop this possibility.