If your immune system is down or your cat is sick, avoid close contact. However it is worth noting that, in general, having a cat in the house can actually improve your health. Many studies suggest that having a pet improves mood, lowers blood pressure and strengthens the immune system. Researchers have also found that children who grow up with animals have fewer allergies, possibly because of early exposure to various bacteria and viruses. If both you and your cat are healthy, a quick peck now and again will not do any harm.