Getting measles is even more dangerous than doctors had realized, because it destroys immunity that the victim has acquired to other diseases, researchers said on Thursday.

The findings help to explain why children often catch other infectious diseases after having measles, and underscore the dangers of growing resistance to childhood vaccination in some countries, according to two studies published simultaneously.

They show for the first time how measles – one of the most contagious diseases – resets the human immune system back to an immature state like a baby’s, with only limited ability to fight off new infections.

The findings have implications for public health globally, since a decline in trust in vaccines, and so in vaccination rates, is leading to outbreaks of measles – which in turn can allow a resurgence of other dangerous diseases such as flu, diphtheria and tuberculosis.