The flu shot works with your immune system, so a compromised system weakens the vaccine's effectiveness. Still, for most people, a little protection is better than none.
What's the difference between a virus and bacteria? Why don't antibiotics kill viruses? Is the five-second rule real or a myth? Fascinating facts about germs.
FAQs about H1N1--the swine flu--with answers from experts. Ask your questions!
A family doctor explains why your nose runs when you have a cold.
A fever sometimes gets higher at night. Learn why.
Learn a family doctor's tips for immune-system boosting—proven ways to strengthen your immune system naturally.
