Question: How do our immune systems get stronger?

Ruth Elderfield answered on 18 Jun 2015:

When we are born we don’t have a very good immune system. It doesn’t know any of the viruses, bacteria or other invaders that want to infect us. Young babies can get antibodies from their Mother’s breastmilk whilst their immune systems are developing. By the time they are 6 months old, the babies can produce their own antibodies.
Antibodies are important as they help to fight the viruses, bacteria and other invaders. The signal other parts of your immune system to kill them.
Your immune system gets stronger as you get older because it is able to remember diseases that have attacked your body before and can destroy them quicker. That is how vaccines work, they help the body create antibodies before they are ever invaded by the virus or bacteria.