My doctor recommends that my 18-month-old son be vaccinated for chickenpox. He has asthma, so I feel he shouldn't get the shot. Am I right?
No. Chickenpox can be dangerous for children with immune-system problems. In fact, before the vaccine was given to all babies, it was used for children with asthma and other immune-system complications, and for children who were currently receiving steroids or who might in the future (which is a definite possibility for your son). The benefits of this vaccine for your child, specifically the prevention of a bad case of chickenpox, far outweigh any drawbacks.
Some experts speculate that children who receive the vaccination may also need a booster when they get older. In fact, studies are being done to see how long immunity will be conferred, according to the American Academy of Pediatrics.