A healthy immune system helps fight off infection every single second of the day, but when it becomes too activated or confused, that's when the problems start. (mindbodygreen.com)
It is one of the greatest gifts that these fragile babies can receive to help fight off infection to an already compromised start. (justbreastfeeding.com)
Many older pets have weakened immune systems that can not fight off disease as well as those of younger pets. (bracpet.com)